Exhausting topic...

Threeweight · **Joined:** Mon May 14, 2007 5:57 pm **Posts:** 679

This has been kicked around a bajillion times in some fashion, but I have a new twist...

In an effort to squeeze a few more MPG's out of my CRD, I had the stock muffler hacked off over the weekend and replaced with a flowtech "Red Hot" glasspack. Much more of an exhaust note now, sounds pretty good driving around town. Fuel economy is up, and the turbo seems to spool up much faster (with a very noticeable wooooosh).

However, on a 260 mile road trip on Monday I was treated to a very nasty resonance within the cabin at speeds between 55 and 70. Not good.

So now I'm contemplating hacking the glasspack off and replacing it with a Flowmaster 50 series, Magnaflow, or a very nice looking $50 Flowmaster rip-off I saw at Knechts tonight (identical in design to the Flowmaster 40).

I'd appreciate any advice/experience folks could share regarding a low restriction, low interior noise muffler option. The wife has sensitive ears, and she ain't happy I hacked that nice quiet muffler off to replace it with a headache machine.

_UnLiMiTeD_ · **Posted:** Wed Feb 27, 2008 2:43 am

50 series delta flow, gain a few mpg from stock, has a nice tone but not super loud either

chrispitude · **Posted:** Wed Feb 27, 2008 7:43 am

Hi Threeweight,

Our CRD is my wife's daily driver, so I erred on the side of caution and installed a Magnaflow 15870 complete cat-back system. It's a stainless steel mandrel-bent system, and was a piece of cake to install. I spent more time sawzalling the factory system off than I did installing the new system (which comes with a sleeve joint in the middle to make assembly a snap). The sound is nearly identical to stock, and I've noticed all the gains that others have (faster spoolup, easier coasting, etc.). My wife described it that the Magnaflow system isn't really any louder, it just sounds like the factory system "went through puberty".

Based on that, a Magnaflow muffler may be worth trying.

- Chris

Turbo Tim · **Posted:** Wed Feb 27, 2008 10:50 am

I just bought the Flowmaster 52572, 70 series (2 1/2 in/out, center in, offset out). On their web site it lists it as one of the quieter ones.

I picked the Flowmaster over the other brands only because there is no packing inside it. Nothing to rot out, or go bad. We use them on our turbo off road cars with no problems.
They use noise cancelling technology without the backpressure. Glasspacks will have backpressure because of the way the ribs are inside. It sets up a standing wave. Most turbos don’t like glasspacks. (Ya I know you can see straight through them, but I have a pile of them that we took off because the turbo’s wouldn’t make full boost. Put the Flowmaster’s on, full boost. You can have the glasspacks).

I made my own 2 ½ inch ID, 3/8 thick, 4-bolt flanges (Carquest exhaust gasket F7153) so I can put the original stuff back in just in case I have to go through an inspection.

I plan on removing all of it, Cat, stock muffler, and just putting the Flowmaster in.

I’ll let you know how it works after this weekend…

geordi · **Posted:** Wed Feb 27, 2008 11:28 am

Turbo Tim wrote:

I just bought the Flowmaster 52572, 70 series (2 1/2 in/out, center in, offset out). On their web site it lists it as one of the quieter ones.

I picked the Flowmaster over the other brands only because there is no packing inside it. Nothing to rot out, or go bad. We use them on our turbo off road cars with no problems.
They use noise cancelling technology without the backpressure. Glasspacks will have backpressure because of the way the ribs are inside. It sets up a standing wave. Most turbos don’t like glasspacks. (Ya I know you can see straight through them, but I have a pile of them that we took off because the turbo’s wouldn’t make full boost. Put the Flowmaster’s on, full boost. You can have the glasspacks).

I made my own 2 ½ inch ID, 3/8 thick, 4-bolt flanges (Carquest exhaust gasket F7153) so I can put the original stuff back in just in case I have to go through an inspection.

I plan on removing all of it, Cat, stock muffler, and just putting the Flowmaster in.

I’ll let you know how it works after this weekend…

Keep us posted Tim! I'm interested too, as I've already decided to pull all the exhaust work out from mine too, and remove the factory jake-brake that is that muffler. But I'm not looking for loud, I'm looking for quiet and efficient. And I'm also going to either remove the cat entirely, or core it. There aren't inspections in Florida or Georgia or South Carolina (Where I'm at right now) so I'm leaning toward pulling it entirely, so I can replace it if I ever need to.

kccrd · **Joined:** Thu Mar 08, 2007 10:35 pm **Posts:** 267

I completely removed my muffler and had the same resonance inside the cabin a little bothersome at times until I installed 5 air tabs on the roof near the back between the ribs on the roof and the resonance went away probably because of the change of air flow at the back of the vehicle is now directed away from the rear of the vehicle and I do not hear that drone. It also gave me much better directional stability when a big semi passes me on a two lane highway. The air tabs are made in Colorado and are very inexpensive to buy I think around 2.50 a piece plus shipping .You hardly notice them when they are installed on my dark green kj . You can paint them to match your vehicle color but I just left mine black.

Turbo Tim · **Posted:** Wed Feb 27, 2008 3:56 pm

Can you get us some pictures? How about a web site or part numbers?
I would be interested in that too along with my "Muffler Mods."

007husky · **Posted:** Wed Feb 27, 2008 5:41 pm

I`m about to do the exhaust myself this weekend and weld a straight pipe (if its too loud i can weld a muffler later).

But looking at the tubing, i noticed a reduction on the exhaust diameter, where the welds are for the flange or for the flex tube before the cat, here is a perfect picture that found on the forum.

http://colorado4wheel.com/images/libby/ ... ilter2.jpg

It looks that the flanges that connect the stock muffler to the cat, have a little bit more restriction than the flex tube weld.

2 questions

1- should I hack the flanges that attach the muffler to the cat ? Or leave them and weld them to the straight pipe or new muffler ?
2- Do they provide considerably backpresure ?

Thanks.

dgeist · **Posted:** Wed Feb 27, 2008 6:24 pm

007husky wrote:

It looks that the flanges that connect the stock muffler to the cat, have a little bit more restriction than the flex tube weld.

2 questions

1- should I hack the flanges that attach the muffler to the cat ? Or leave them and weld them to the straight pipe or new muffler ?
2- Do they provide considerably backpresure ?

Thanks.

X2 interested in response. Had originally only thought of replacement of the muffler with straight-pipe, But if the cat is not actually a cat, then replacing it would seem reasonable (and also potentially legal) too.

Dan

Joe Romas · **Posted:** Wed Feb 27, 2008 7:04 pm

In one of the past threads on this subject someone found a flange that you would weld to a stright pipe or muffler then would bolt to our cats. That flange would make reinstalling the original easy if needed and would make for a cleaner install :lol:

Turbo Tim · **Posted:** Wed Feb 27, 2008 8:42 pm

That’s the problem. Finding good thick flanges. I looked high and low and couldn’t find decent ones. I wanted something 3/8 or ½ inch thick that won’t bend when tightened. Not like those cheesy header flanges.
So I just made my own. Cost so far is around $25 for 6 flanges.

Now I can take both original items (Cat & muffler), weld flanges on them, and they’re ready to go back in if need be. The CRD side will have the same flanges welded on, right after the flex tube (before cat) and just after the stock muffler.
Now I can put my Flowmaster on with a set of matching flanges.
Now I have options. If I don’t like the way the Flowmaster sounds, I can put two on, or a different muffler.

The point is that no bridges were burned. I can go back to stock in about 5 minutes time.

kccrd · **Joined:** Thu Mar 08, 2007 10:35 pm **Posts:** 267

If anybody is interested the airtabs I placed on my roof can be found at airtab.com or 1.888.382.7384 they are located in windsor, colorado my part #s were atblack 02 they charged me $2.50 a piece.

DarbyWalters · **Posted:** Wed Feb 27, 2008 11:47 pm

Air Tabs...three on each side (going to add one to each side) and five across the roofline:

3" Exhaust with no muffler:

Tailpipe a bit longer:

And my new Lambretta DUE 50cc 2 Stroke Moped...got 114 MPG the first fillup:

Joe Romas · **Posted:** Thu Feb 28, 2008 8:21 am

Darby.

I've not herd Lambretta mentioned since about 1960 :shock:

Do you have a Bella also :?:

(remember those?)

Joe

DarbyWalters · **Posted:** Thu Feb 28, 2008 9:16 am

Maybe you mean Stella ... another brand ... The real Lambrettas are about to be reintroduced also. This is a Taiwan (not a bad thing ) scooter. It is the same as an Adly Panther 50 (2T).

The Vespa, Lambretta and Genuine Scooters (Stella) are all making a comeback now.

Joe Romas · **Posted:** Thu Feb 28, 2008 6:48 pm

DarbyWalters wrote:

Maybe you mean Stella ... another brand ... The real Lambrettas are about to be reintroduced also. This is a Taiwan (not a bad thing ) scooter. It is the same as an Adly Panther 50 (2T).

The Vespa, Lambretta and Genuine Scooters (Stella) are all making a comeback now.

Nope. The Bella was made by Zundapp and screamed. Here's a link.
http://www.provost.org/Bella/History.asp

Joe

Threeweight · **Joined:** Mon May 14, 2007 5:57 pm **Posts:** 679

Drone solved (I hope) today with the installation of a Flowmaster 50 series deltaflow muffler. Thank's for the suggestion _UnLiMiTeD_.

So far, sound is about the same as stock, a little deeper. Still get the nice woooosh of turbo when stomping on the gas. Fuel economy looks to be unchanged from the glasspack.

007husky · **Posted:** Sun Mar 02, 2008 1:29 am

Installed a straight pipe tonight.

Welded 2 2.5 ID tail pipes back to back to correct the offset of 3 inches between the old muffler and the cat
took the flanges out becouse reduced the ID to 2.

Truck really feels more responsive and cruises much nicer.

geordi · **Posted:** Sun Mar 02, 2008 2:18 am

Is there any substantial reason to go with a 3" exhaust?

How is the noise level with your straightpipe? I'm getting so frustrated with the Jeep's lack of coasting ability... I have a bridge I have to cross every day, this thing is a mile long, and rises an EASY 200' above the waterline... It's a steep climb, and coasting down the other side, the KJ doesn't pick up any speed unless I kick it out of gear. I leave it in gear, and I can totally feel the restriction.

I'm leaning toward cutting in between the flange (if there is one) upstream of the cat, and the cat, and again between the muffler and the final flange (if there is one) to preserve the flanges, and just clamp or weld in a straight pipe. If I can maintain the stock tail, I'm fine with that, it's just a tailpipe anyway.

007husky · **Posted:** Sun Mar 02, 2008 12:12 pm

geordi wrote:

Is there any substantial reason to go with a 3" exhaust?

How is the noise level with your straightpipe? I'm getting so frustrated with the Jeep's lack of coasting ability... I have a bridge I have to cross every day, this thing is a mile long, and rises an EASY 200' above the waterline... It's a steep climb, and coasting down the other side, the KJ doesn't pick up any speed unless I kick it out of gear. I leave it in gear, and I can totally feel the restriction.

I'm leaning toward cutting in between the flange (if there is one) upstream of the cat, and the cat, and again between the muffler and the final flange (if there is one) to preserve the flanges, and just clamp or weld in a straight pipe. If I can maintain the stock tail, I'm fine with that, it's just a tailpipe anyway.

It is not much louder, just more rumbly. It really doesn't bother me at all. And you can always add a mufler later on.

it only cost me less than 15 bucks too.

what i did was :

original:

tail pipe section,---arround axel ------ muffler --- flange ---- cat --- flex pipe---- turbo.

mine:

tail pipe section--- arround muffler------ 2.5 id pipe -- welded 2 2.5 exhaust tail pipes --- cat --- flange-- flex pipe --- turbo.

The flanges that atach the mufler and cat originally are a botleneck. so i cut them off. I used slip on pipes from autozone and exhaust camps to conect my welded part to the tail pipe section and cat. So if i want to take it off and add a diferent muffler i can easly. But i probably wont cos i think is ok.

I just started welding, and this pipe was like suck booty soft, so my welds are horrible ! no laffing allowed

Pic of the flange:

pic of the outside of flange, you can tell where the welds are how it chokes the pipe. is really clear on the inside pic.

pic of the 2 tailpies from autozone,

pic of the final result

Notice my riging finishes before the axel to use as much as i can of the factory bent pipe that goes from before the axel to the tailpipe !

Exhausting topic...

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