Installing Magnaflow Muffler

Mountainman · **Posted:** Mon Jan 12, 2015 3:32 pm

ok, thanks man! so that gets rid of the narrow bit by the cat? and you can notice it being a bit louder at cruising speed? I want that 1/10th of a mpg or whatever it may be, but I don't want anything getting in the way of my XM radio, as my hearing is pretty bad anyhow :furious:

Diver1430 · **Posted:** Mon Jan 12, 2015 6:20 pm

I cut out the cat and the muffler and saved same. Pretty good shape. Installed a flowmaster 40 series street muffler #942542 which I got out of the Summit catalog. Sounds a little throaty but nothing compared to the stuff I owned in the 60's or my cummings. No change in the cabin. Have GDE tune, ran two tanks of rack fuel and saw no definite mileage change. I get 21.5 to 22.5 calculated and show 21 on my overhead.

thermorex · **Posted:** Mon Jan 12, 2015 7:28 pm

Mountainman wrote:

ok, thanks man! so that gets rid of the narrow bit by the cat? and you can notice it being a bit louder at cruising speed? I want that 1/10th of a mpg or whatever it may be, but I don't want anything getting in the way of my XM radio, as my hearing is pretty bad anyhow :furious:

You'll hear the engine over the growl on the highway, don't worry. Crd doesn't do a good job keeping the noises down in the cabin. I straight piped the 4.0 on the Cherokee and the offroad tires make a louder sound than the muffler, lol. I think you'll like it. If you wanna play safe, put 2 clamps so you can replace it later if you don't like it.

Mountainman · **Posted:** Mon Jan 12, 2015 8:14 pm

thanks fellas! I'm excited to gut the muffler, and maybe get a tiny boost out of it, and the added growl will make me think my little four banger is bigger :5SHOTS:

Maybe cool the EGT a bit also?

Maver1ck · **Posted:** Sat Jan 17, 2015 9:33 am

black dog wrote:

fish1 wrote:

Straight pipe no muffler,works for me.

X3

X4

WWDiesel · **Posted:** Sat Jan 17, 2015 10:55 am

You will love the sound of a low restriction muffler and it will help lower EGT's somewhat. Lower back pressure on the turbo outlet will also be less which will slightly help shorten turbo response time. :wink:

Key to good diesel performance: Low restriction air in to turbo and low restriction exhaust out of turbo...
I have a Flowmaster with no CAT and love the mellow sound. As thermorex stated, the engine sounds will be louder than the exhaust tone going down the road....

DOC4444 · **Posted:** Sun Jan 18, 2015 3:53 pm

Keith at GDE has gone on record that deleting or "cleaning" the CAT results in absolutely no performance benefit. Unfortunately, this was issued AFTER I had already "cleaned" mine. BTW, if you do decide to "clean", you can supposedly get $200 from a rare materials recycler, so do not throw the contents out.

The reason I kept my cannister in place was in case the state inpection process starts including visual confirmation of the presence of a "CAT".

At the moment, I live in Mass. They just plug into the OBDII port and scan for certain codes. With a GDE tune, even with "Weeks" elbow and EGR valve deleted, I was able to pass state inspection, yesterday.

I have a Magnaflow "cat back" "stainless" exhaust system. It is actually for the 3.7 gas version. It fits fine, but with the first one, the muffler rusted out at the welded seems and came apart in three years. Their customer service was beyond abysmal. It took three months, before they agreed to honor their "lifetime" warranty, based on crystal clear photo evidence. Then they insisted I pay full retail for another system. The new one arrived dented. They would not replace that one. On top of THAT, they took FOUR MONTHS to finally refund my credit card for the 2nd purchase and return shipping. The whole process took SEVEN months to complete and involved over 20 phone calls and 30 emails.

DOC

WWDiesel · **Posted:** Sun Jan 18, 2015 4:55 pm

If you do not have to leave the CAT as Doc stated for visual inspection; you can order a Flowmaster muffler from Advance with 2 1/4 in/out for a little over 80 bucks. Remove the CAT and the reducer in front of it and replace it all with 2 1/4 inch straight pipe into muffler.
The reducer and the CAT are the restrictions in the exhaust system along with the muffler...
Some on this forum have reported some MPG increase after performing the above modifications... Power increase, judge for yourself...
Lowering exhaust back pressure on the turbo WILL decrease EGT's out of the engine; I know this for a fact from the modes I did on my Dodge Cummins with EGT and boost gauges. (5 inch turbo back exhaust)
A Diesel engine is a big old air pump, the more air you can get in and out with the least restriction the more power it will produce. Valve size and head flow dynamics are the main limiting factors if you diminish all others.

Mountainman · **Posted:** Wed Jan 21, 2015 3:06 pm

thanks for all of the additional info everyone! :rockon:

Installing Magnaflow Muffler

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