2 1/2 or 3 inch straight pipe?

LS12FAST4U · **Posted:** Thu Mar 06, 2014 5:48 pm

Just wondering if anyone has ever straight piped their CRD? I currently have cut out the muffler and just added a piece of 2 1/2 inch exhaust pipe there but I would like it a little louder and possibly more turbo noise.

Glend · **Posted:** Thu Mar 06, 2014 7:18 pm

There are plenty of past discussion on this topic, just use the search function to find them. Based on laminar flow arguments, a 2 1/2" pipe is the choice for the KJ CRD, any bigger and you actually reduce flow. You can get away with a straight pipe as the turbo serves as a muffler in part. Just make sure you eliminate the various restrictions around flanges and clamps.

LS12FAST4U · **Posted:** Mon Mar 10, 2014 10:30 pm

I was more concerned about sound rather then power. Remember we drive a diesel liberty its not a drag strip car. I don't care if it gains 1 hp or loses 5 I just want it to sound like a diesel truck.

racertracer · **Posted:** Mon Mar 10, 2014 10:57 pm

Going on what past members have experienced when doing the 3" mod instead of the 2 1/2".

The 3" didn't increase the diesel sound, it reduced it and it didn't increase any more performance than the 2 1/2" mod. It was a useless modification.

WWDiesel · **Posted:** Tue Mar 11, 2014 11:36 am

Glen,
I replaced CAT with 2 1/2 straight pipe eliminating the restriction point just in front of the CAT flange. Put on a Flow Master 2 1/2 in and out muffler. Great sound and helped power a little bit. Sound to me is just right, not too loud, and enough to let you know it is a diesel!!! :JEEPIN:

2 1/2 or 3 inch straight pipe?

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