New guy exhaust mod question

coldkj · **Posted:** Tue May 22, 2007 2:44 am

Ok, this may be a dumb or redundant question, but here goes. Can someone help me sort out the different free flow options for my CRD? I'm maily interested in mileage, but performance would be a secondary goal. I've only done the ORM mod and an ARB bumber so far, and am getting about 22 mpg in town and about 25 on the open road (in summer, 2wd, summer fuel). It seems like the magnaflow and the aeroturbo 2525 are the most popular exhaust mods I've read about. Is there any science to this discussion? thanks.

onthehunt · **Posted:** Tue May 22, 2007 2:55 am

The aero muffler is quite large and protrudes from the bottom. That eliminated the muffler for me. I used a magnaflow I think. 3" in and 3" out. The stock exhaust is 3" except at the muffler where they pinched it down to 2 1/2" so they could use a single muffler across the liberty line.

DarbyWalters · **Posted:** Tue May 22, 2007 7:25 am

I believe stock is 2.5" and pinches down in a couple of places.

skywarn · **Posted:** Tue May 22, 2007 9:21 am

magnaflow best for the price and is low profile its the next best thing to not running a muffler. should only cost ya $150 installed.

spoonplugger1 · **Posted:** Tue May 22, 2007 11:52 am

I put the FlowMaster 40 Delta on mine, was cheaper, small, and the stock exhaust is mandrel bent 2 1/2 inch pipe. The same as the aftermarket exhausts. A glasspack muffler would probably do just as well for half the cost or less. I don't think your going to notice much difference, I didn't. Moderate use of the loud peddle is the only thing I've done that helps, the ARB bumper probably didn't help you any.

skywarn · **Posted:** Tue May 22, 2007 2:17 pm

just be sure which ever muffler you do go with, thats its a stright through design. anything with "chambers" or Baffles are bad... all you want is something that looks like a muffler to pass inspec. with the least amount of back pressure as possable

if your state doesnt require a muffler then go with just a stright pipe.

GilaMonster · **Posted:** Tue May 22, 2007 8:17 pm

I installed a Dynomax muffler with good results. It is basically a more complicated cherry bomb. I also removed the step down flange and welded in 2.5 flanges at the cat and the other end. Then just welded flanges on the muffler. It sits up good and is not hanging down where it could get bashed wheelin.

I'm happy with the results, as always YMMV.

coldkj · **Posted:** Tue May 22, 2007 8:43 pm

Thanks for the feedback guys. The Magnaflow looks like it might be the lowest hassle-factor for a replacement muffler. You're right abut the ARB. Didn't help my mileage, but didn't hurt it a ton either. Right around the time I mounted that beast we changed to winter fuel, I had a roof-top tent from Maggiolina on top, and my commute to work dropped to just under 2 miles. And we had a colder winter than usual. And I drove around in 4wd most of the winter because we had a lot of snow. All in all, recipe for crummy mileage. Now, however, with ORM, better fuel, warmer ambient temp and 2wd, my mileage is as good, or a little better, than it ever was. BTW, I have 13000 miles on now.

Anyway, thanks again for the info on the mufflers.

Anomious · **Posted:** Mon May 28, 2007 12:47 am

Hi! I used a Stainless steel "Chambered" muffler from SummitRacing. 2 1/2" in and out, straight through,26" body 30" total length. 4" OD. SUM-630725P .
Looks good, sounds good! LK :wink:

retmil46 · **Posted:** Mon May 28, 2007 9:05 am

Just about any of the options mentioned will be an improvement over the stock muffler. For '05, DC used the same stock muffler on the 2.4 L and 3.7 L gas versions AND the CRD. I examined mine when it was removed. Bloody thing is so incredibly restricted as to be beyond belief, nothing but a large soot trap.

Way back when, before DC started playing with reflashes and detuning the engine, some of us early exhaust modders did notice an improvement in throttle response and some increase in fuel mileage. Those that were able to monitor EGT's noticed a reduction in exhaust gas temps as well.

Stock exhaust system is 2 1/2", necked down to 2" between the 2 bolt flange and the front of the muffler (one pipe slid inside another) and on the outlet of the stock muffler.

New guy exhaust mod question

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