LOST JEEPS :: View topic - Aftermarket Muffler vs. Straight Pipe

It's a known fact that Flowmaster mufflers have the best sound on the market... but they kill gasoline engines. Kiss your torque goodbye if you put a FM on your ride.

LibertyCRD wrote:

It's a known fact that Flowmaster mufflers have the best sound on the market... but they kill gasoline engines. Kiss your torque goodbye if you put a FM on your ride.

Where is this documented?

It's a known fact that Flowmaster mufflers have the best sound on the market... but they kill gasoline engines. Kiss your torque goodbye if you put a FM on your ride.

My opinion would be to stick with Magnaflow or Dynomax. The factory piping is fine on newer vehicles these days... just have a shop cut your OEM muffler off and weld up the muffler of your choice in it's place.

It's a piece of cake to remove the rear section of the exhaust on a KJ... so what I do is just remove it and then you can work on it outside of the Jeep. It's much easier that way.

I've done mine twice now....
First time I cut the stock muffler off tight to the muffler....(a saws all with a metal cutting blade comes in handy for this).
The stock piping on the KJ reduces from 2.5" to 2.25" just before the muffler, then exits the muffler at 2.25" then increases to 2.5" going into the tail pipe. I left the 2.25" sections intact, and purchased a Thrush Turbo muffler with 2.25" fittings, one clamp on the inlet side, an 18" X 2.25" extension pipe on the outlet side cut to fit to the tail pipe, 2 clamps there, and I was done......so I thought. I ran it this way for a few months, I did gain HP, throttle response, and a slight increase in mileage, but after reading a few threads about cutting the stock piping back to where it's 2.5", and going with a performance muffler with 2.5" fittings being better.....well I had to try it and see, so this time I got a Thrush welded muffler, some 2.5" clamps, a short length of 2.5" extension pipe and a 2.5" turn down. I cut the bolted flange off where the piping is 2.5", slid the welded Thrush right on and clamped it. On the outlet side I fitted the extension piece with the turn down clamped on the end of that so it ends just before the rear axle, added a universal hanger at the turn down, and now it has a pinch more throttle response, sounds awesome, but the jury is still out on any improvements with mileage.....

This set up can be either clamped or welded, if you have the means to weld, then that's the better way to go, I do not have a welder, so I used clamps, besides when I have to go through emissions inspection in 12 months from now, I'll have to put my tail pipe back on or run the risk of failing due to an improper exhaust system, if I welded it I wouldn't be able to do that too easy.....

Thanks for the information! I am going to cut the stock piping where it's 2.5" and get a muffler with 2.5" fittings. Did the mufflers you bought have a center inlet and offset outlet? Why did you choose Thrush?

All over the Internet. Just use Google.

I even know of one case where a guy installed a Flowmaster, and lost 20 lb/ft of torque on the Dyno immediately. Again, this is with gasoline engines. I haven't seen many diesel guys use Flowmaster so I suppose the jury would still be out on that.

Well I got tired of my straight pipe and put on a Thrush Turbo muffler the other day. Got it for $27.99 at the local Advance Auto Parts. :mrgreen:

It's 2.5" inlet and outlet. I immediately noticed more low end grunt. Today I still feel the extra torque down low. And, the Jeep is more quiet and close to stock noise level. This muffler is by far the best $28 I have ever spent so far on this diesel. And I got a 12 month warranty too.

I highly recommend the muffler I use (see my signature). I've been through a bunch of cheapos and they just don't compare to the sound or quality of the Dynomax!

LibertyCRD wrote:

Well I got tired of my straight pipe and put on a Thrush Turbo muffler the other day. Got it for $27.99 at the local Advance Auto Parts. :mrgreen:

So, after telling me that Flows kill torque, you buy a Flow knockoff and it increases the torque you feel?lol

You dont know how much I appreciate this post. I currently have a super 44 that I LOVE the sound and performance of it (I didnt see any loss in torque according to the butt dyno), but the darn thing is nearly rotten through in less then a year. We get alot of precipatation in the fall and winter time and ALOT of salt and apparently the super 44 couldnt take it. SO I asked for the dynomax cat back with the SS ultra flow. Reason I went with the cat back over just the muffler like I did the first time is I kinda wanted a nice tasteful tip for mall crawling and when I initially did the FM install I just sawsall'd it and clamped it (big mistake as it not only started to leak but also shrunk the pipe in 2 spots) and I dont want the crimp from the clamps anymore. Plus Im getting excited about having a slightly quieter exhaust for those late night runs to the office.

Author:	Carmodifier [ Mon Oct 04, 2010 2:48 am ]
Post subject:	Aftermarket Muffler vs. Straight Pipe
I have been doing a lot of research for a new exhaust system for my KJ; I have browsed multiple threads from various forums and watched numerous YouTube video clips. After all my research, I have decided to just replace the OEM muffler with an aftermarket muffler. I am interested in the following mufflers: Flowmaster Super 10 Series [http://tiny.cc/lnhhh], Flowmaster Super 44 [http://tiny.cc/qulf6pwpnv], Cherry Bomb Glasspack [http://tiny.cc/x53xw], or straight pipe. My goal is to increase HP and torque while also improving gas mileage; I am not expecting huge gains though. An aggressive sound is also very important when choosing my muffler. What muffler would you recommend I install on my KJ? What inlet/outlet muffler size should I get, 2.25" or 2.5"? I believe it is 2.5", but I have heard people recommend both sizes. I believe I need to get a muffler with a center inlet and offset outlet. Am I correct on this? What is the best method of installing the muffler, welding or just simply bolting it on? Feel free to post photos and videos of your exhaust set-up! Thanks in advance for your help!

Author:	LibertyCRD [ Mon Oct 04, 2010 7:39 am ]
Post subject:	Re: Aftermarket Muffler vs. Straight Pipe
It's a known fact that Flowmaster mufflers have the best sound on the market... but they kill gasoline engines. Kiss your torque goodbye if you put a FM on your ride. My opinion would be to stick with Magnaflow or Dynomax. The factory piping is fine on newer vehicles these days... just have a shop cut your OEM muffler off and weld up the muffler of your choice in it's place. It's a piece of cake to remove the rear section of the exhaust on a KJ... so what I do is just remove it and then you can work on it outside of the Jeep. It's much easier that way.

Author:	SurfGuitar141 [ Mon Oct 04, 2010 7:15 pm ]
Post subject:	Re: Aftermarket Muffler vs. Straight Pipe
I've done mine twice now.... First time I cut the stock muffler off tight to the muffler....(a saws all with a metal cutting blade comes in handy for this). The stock piping on the KJ reduces from 2.5" to 2.25" just before the muffler, then exits the muffler at 2.25" then increases to 2.5" going into the tail pipe. I left the 2.25" sections intact, and purchased a Thrush Turbo muffler with 2.25" fittings, one clamp on the inlet side, an 18" X 2.25" extension pipe on the outlet side cut to fit to the tail pipe, 2 clamps there, and I was done......so I thought. I ran it this way for a few months, I did gain HP, throttle response, and a slight increase in mileage, but after reading a few threads about cutting the stock piping back to where it's 2.5", and going with a performance muffler with 2.5" fittings being better.....well I had to try it and see, so this time I got a Thrush welded muffler, some 2.5" clamps, a short length of 2.5" extension pipe and a 2.5" turn down. I cut the bolted flange off where the piping is 2.5", slid the welded Thrush right on and clamped it. On the outlet side I fitted the extension piece with the turn down clamped on the end of that so it ends just before the rear axle, added a universal hanger at the turn down, and now it has a pinch more throttle response, sounds awesome, but the jury is still out on any improvements with mileage..... This set up can be either clamped or welded, if you have the means to weld, then that's the better way to go, I do not have a welder, so I used clamps, besides when I have to go through emissions inspection in 12 months from now, I'll have to put my tail pipe back on or run the risk of failing due to an improper exhaust system, if I welded it I wouldn't be able to do that too easy.....

Author:	67Customs [ Mon Oct 04, 2010 8:19 pm ]
Post subject:	Re: Aftermarket Muffler vs. Straight Pipe
LibertyCRD wrote: It's a known fact that Flowmaster mufflers have the best sound on the market... but they kill gasoline engines. Kiss your torque goodbye if you put a FM on your ride. Where is this documented?

Author:	LibertyCRD [ Mon Oct 04, 2010 10:45 pm ]
Post subject:	Re: Aftermarket Muffler vs. Straight Pipe
67Customs wrote: LibertyCRD wrote: It's a known fact that Flowmaster mufflers have the best sound on the market... but they kill gasoline engines. Kiss your torque goodbye if you put a FM on your ride. Where is this documented? All over the Internet. Just use Google. I even know of one case where a guy installed a Flowmaster, and lost 20 lb/ft of torque on the Dyno immediately. Again, this is with gasoline engines. I haven't seen many diesel guys use Flowmaster so I suppose the jury would still be out on that.

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Author:	Carmodifier [ Mon Oct 04, 2010 11:14 pm ]
Post subject:	Re: Aftermarket Muffler vs. Straight Pipe
LibertyCRD wrote: It's a known fact that Flowmaster mufflers have the best sound on the market... but they kill gasoline engines. Kiss your torque goodbye if you put a FM on your ride. My opinion would be to stick with Magnaflow or Dynomax. The factory piping is fine on newer vehicles these days... just have a shop cut your OEM muffler off and weld up the muffler of your choice in it's place. It's a piece of cake to remove the rear section of the exhaust on a KJ... so what I do is just remove it and then you can work on it outside of the Jeep. It's much easier that way. I still don't understand how Flowmaster mufflers kill gasoline engines... On my Acura, I did custom 3" mandrel bent tubing from the cat-back to dual 3" inlet/4" outlet MagnaFlow Race Series mufflers [http://tiny.cc/byyvk]. They look and sound great, especially in low RPMs. In high RPMs, the intake overpowers the sound of the exhaust. It was recommended to remove my cat, but I don't want to deal with the computer problems and smell that results of that action. Thus, I am considering swamping out my OEM cat with a high flow cat to see if that helps me get more of a rumble in high RPMs. What MagnaFlow and Dynomax mufflers would you recommend? I am hoping a buddy of mine, who owns a welder, will help me install my muffler. If he doesn't feel he can do a good job, I'll bring it to a shop to have it professionally installed.

Author:	audiboy86 [ Mon Oct 04, 2010 11:18 pm ]
Post subject:	Re: Aftermarket Muffler vs. Straight Pipe
I on a CRD and i used the cherry bomb kit with the new vortex style like it way better then the glass pack and way better then the flowmaster i had first. Plus now i can here my turbo real nice and clear and it sounds like a SB chevy off the line. But if it is a gasser i have no idea which way to go.

Author:	Carmodifier [ Mon Oct 04, 2010 11:26 pm ]
Post subject:	Re: Aftermarket Muffler vs. Straight Pipe
SurfGuitar141 wrote: I've done mine twice now.... First time I cut the stock muffler off tight to the muffler....(a saws all with a metal cutting blade comes in handy for this). The stock piping on the KJ reduces from 2.5" to 2.25" just before the muffler, then exits the muffler at 2.25" then increases to 2.5" going into the tail pipe. I left the 2.25" sections intact, and purchased a Thrush Turbo muffler with 2.25" fittings, one clamp on the inlet side, an 18" X 2.25" extension pipe on the outlet side cut to fit to the tail pipe, 2 clamps there, and I was done......so I thought. I ran it this way for a few months, I did gain HP, throttle response, and a slight increase in mileage, but after reading a few threads about cutting the stock piping back to where it's 2.5", and going with a performance muffler with 2.5" fittings being better.....well I had to try it and see, so this time I got a Thrush welded muffler, some 2.5" clamps, a short length of 2.5" extension pipe and a 2.5" turn down. I cut the bolted flange off where the piping is 2.5", slid the welded Thrush right on and clamped it. On the outlet side I fitted the extension piece with the turn down clamped on the end of that so it ends just before the rear axle, added a universal hanger at the turn down, and now it has a pinch more throttle response, sounds awesome, but the jury is still out on any improvements with mileage..... This set up can be either clamped or welded, if you have the means to weld, then that's the better way to go, I do not have a welder, so I used clamps, besides when I have to go through emissions inspection in 12 months from now, I'll have to put my tail pipe back on or run the risk of failing due to an improper exhaust system, if I welded it I wouldn't be able to do that too easy..... Thanks for the information! I am going to cut the stock piping where it's 2.5" and get a muffler with 2.5" fittings. Did the mufflers you bought have a center inlet and offset outlet? Why did you choose Thrush?

Author:	SurfGuitar141 [ Tue Oct 05, 2010 8:36 am ]
Post subject:	Re: Aftermarket Muffler vs. Straight Pipe
Carmodifier wrote: Thanks for the information! I am going to cut the stock piping where it's 2.5" and get a muffler with 2.5" fittings. Did the mufflers you bought have a center inlet and offset outlet? Why did you choose Thrush? I'm an old guy from the old school muscle car era, back then Thrush and Cherry Bomb were pretty much all we had to work with, I always put Thrush mufflers on everything I've had, I just stick with what I know works.... Both the standard Turbo...(seamed)....muffler, and the new welded muffler come with offset piping, the older style turbo does not indicate inlet or outlet, and is a universal fit, the welded however does indicate outlet on the end where the fitting is centered, the issue here is, on the Liberty that's the end you want as your inlet. I slipped and clamped it on both ways to see if it made any difference, and didn't see any, so I installed it backwards so it would fit properly, line up with the stock tail pipe, and not hit the drive shaft.....

Author:	67Customs [ Tue Oct 05, 2010 9:10 am ]
Post subject:	Re: Aftermarket Muffler vs. Straight Pipe
LibertyCRD wrote: All over the Internet. Just use Google. I even know of one case where a guy installed a Flowmaster, and lost 20 lb/ft of torque on the Dyno immediately. Again, this is with gasoline engines. I haven't seen many diesel guys use Flowmaster so I suppose the jury would still be out on that. I have searched the internet. Nobody that I have seen shows ultimate proof it was the muffler. They have changed out other things as well and then blame it on the muffler. On one, the guy had near 800 whp and he lost a few HPs and Lbs, but on a high-perf motor like that, little changes can mean big increases/decreases. It isn't going to effect my stock motor the same. Then, there are the people who just claim certain things with no proof at all. The internet is absolutely full of that garbage. I have ran Flowmaster mufflers on several vehicles from I4s to V8s and I've never "felt" a torque decrease. If I did, I would have ripped it right off. I'm not saying that it is impossible and I'm not a die hard Flowmaster fan at all. I am seriously considering the Maganaflow. But I've never had a problem with Flowmaster except for expereiencing some drone on a couple of friends vehicles. Although, they were pushing a good amount of HP with nothing but a little sheet metal in between the muffler and the cabin with a dumped muffler. I feel that the Magnaflow doesn't give as deep a sound or is agressive, but I know I'm not going to get interior droan. But, I am still considering the Flowmstaer as well because I like the sound better (based on Youtube videos). Magnaflow people aren't putting up good videos or something. It sounds to much like V6 motor in a car that a V6 motor in a SUV. I'm not sure I like that. The videos could be decieving though. What I really need is for people to explain the difference in the Magnaflow mufflers. Flowmasters website does a great job of listing them in aggression order. I don't get the same user friendly feeling out of the Magnaflow site.

Author:	Carmodifier [ Thu Oct 07, 2010 1:29 am ]
Post subject:	Re: Aftermarket Muffler vs. Straight Pipe
SurfGuitar141: According to you, I should get a muffler with a center inlet and offset outlet. Am I correct on this? 67Customs: I agree, Flowmaster does a great job listing their mufflers in order of aggression. I wish other manufacturers (e.g. MagnaFlow, Cherry Bomb, Thrush, Dynomax, etc.) would do the same. Can someone state each manufacture's most aggressive muffler? I am really considering the Flowmaster Super 10, since this is their loudest and most aggressive muffler. I just hope it's not too overbearing and get me in trouble with the local PD. Does anyone have any experience and/or insight on this muffler?

Author:	audiboy86 [ Thu Oct 07, 2010 10:31 am ]
Post subject:	Re: Aftermarket Muffler vs. Straight Pipe
Well i know that cherry bomb produces three mufflers that are considered extremely loud. That is the vortex, pro and extreme. In that order extreme being the loudest and the smallest prefect for offroad. The more i read about it the more i think abou swapping my Vortex out for it.

Author:	SavageUrge [ Tue Oct 12, 2010 3:29 pm ]
Post subject:	Re: Aftermarket Muffler vs. Straight Pipe
I highly recommend the muffler I use (see my signature). I've been through a bunch of cheapos and they just don't compare to the sound or quality of the Dynomax!

Author:	LibertyCRD [ Tue Oct 12, 2010 7:46 pm ]
Post subject:	Re: Aftermarket Muffler vs. Straight Pipe
Well I got tired of my straight pipe and put on a Thrush Turbo muffler the other day. Got it for $27.99 at the local Advance Auto Parts. It's 2.5" inlet and outlet. I immediately noticed more low end grunt. Today I still feel the extra torque down low. And, the Jeep is more quiet and close to stock noise level. This muffler is by far the best $28 I have ever spent so far on this diesel. And I got a 12 month warranty too.

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Author:	67Customs [ Fri Oct 15, 2010 7:55 am ]
Post subject:	Re: Aftermarket Muffler vs. Straight Pipe
LibertyCRD wrote: Well I got tired of my straight pipe and put on a Thrush Turbo muffler the other day. Got it for $27.99 at the local Advance Auto Parts. It's 2.5" inlet and outlet. I immediately noticed more low end grunt. Today I still feel the extra torque down low. And, the Jeep is more quiet and close to stock noise level. This muffler is by far the best $28 I have ever spent so far on this diesel. And I got a 12 month warranty too. So, after telling me that Flows kill torque, you buy a Flow knockoff and it increases the torque you feel?lol

Author:	tommudd [ Fri Oct 15, 2010 7:58 am ]
Post subject:	Re: Aftermarket Muffler vs. Straight Pipe
Thursh Turbo is hardly a Flow knockoff

Author:	liquidxit2 [ Fri Oct 15, 2010 11:43 am ]
Post subject:	Re: Aftermarket Muffler vs. Straight Pipe
SavageUrge wrote: I highly recommend the muffler I use (see my signature). I've been through a bunch of cheapos and they just don't compare to the sound or quality of the Dynomax! You dont know how much I appreciate this post. I currently have a super 44 that I LOVE the sound and performance of it (I didnt see any loss in torque according to the butt dyno), but the darn thing is nearly rotten through in less then a year. We get alot of precipatation in the fall and winter time and ALOT of salt and apparently the super 44 couldnt take it. SO I asked for the dynomax cat back with the SS ultra flow. Reason I went with the cat back over just the muffler like I did the first time is I kinda wanted a nice tasteful tip for mall crawling and when I initially did the FM install I just sawsall'd it and clamped it (big mistake as it not only started to leak but also shrunk the pipe in 2 spots) and I dont want the crimp from the clamps anymore. Plus Im getting excited about having a slightly quieter exhaust for those late night runs to the office.

Author:	LibertyCRD [ Fri Oct 15, 2010 12:45 pm ]
Post subject:	Re: Aftermarket Muffler vs. Straight Pipe
67Customs wrote: LibertyCRD wrote: Well I got tired of my straight pipe and put on a Thrush Turbo muffler the other day. Got it for $27.99 at the local Advance Auto Parts. It's 2.5" inlet and outlet. I immediately noticed more low end grunt. Today I still feel the extra torque down low. And, the Jeep is more quiet and close to stock noise level. This muffler is by far the best $28 I have ever spent so far on this diesel. And I got a 12 month warranty too. So, after telling me that Flows kill torque, you buy a Flow knockoff and it increases the torque you feel?lol You're thinking about Thrush Welded. It is similar to the Flowsucker. Actually, the FM is similar to the Thrush since the Thrush was around first. The muffler I got is the Thrush Turbo. 100% different muffler inside and out. And yes... my grunt down low is improved now somewhat and currently I'm at 350 miles on this tank with a full 1/4 tank to go...so it's a decent fuel economy tank for me too. I'm very happy. Especially for $28 bucks.

Author:	Carmodifier [ Sat Oct 16, 2010 2:01 am ]
Post subject:	Re: Aftermarket Muffler vs. Straight Pipe
liquidxit2 wrote: You dont know how much I appreciate this post. I currently have a super 44 that I LOVE the sound and performance of it (I didnt see any loss in torque according to the butt dyno), but the darn thing is nearly rotten through in less then a year. We get alot of precipatation in the fall and winter time and ALOT of salt and apparently the super 44 couldnt take it. SO I asked for the dynomax cat back with the SS ultra flow. Reason I went with the cat back over just the muffler like I did the first time is I kinda wanted a nice tasteful tip for mall crawling and when I initially did the FM install I just sawsall'd it and clamped it (big mistake as it not only started to leak but also shrunk the pipe in 2 spots) and I dont want the crimp from the clamps anymore. Plus Im getting excited about having a slightly quieter exhaust for those late night runs to the office. I am leaning towards going with the FlowMaster Super 44 and welding it, not clamping. However, reading this post makes me a little weary of going with this muffler since I live in MN and am exposed to all four seasons. Is it common for the Super 44 to deteriorate and rot like this? Has this happened to anyone else?