Back pressure
Diesel Bomber
Joined: Nov 2009
Posts: 1,058
Likes: 53
From: Sanford, Colorado
Naw if the engine is running the turbo is gettin oil has nothing to do with back pressure or having a muffler on it. I straight piped mine a month ago and love the way it sounds the only regret i have is that i didnt do it sooner. 
Site Sponsor
Joined: Apr 2009
Posts: 3,719
Likes: 636
From: Lexington SC
not true dyno proven that you will build boost faster and your motor will run mode efficient at lower RPM with some kind of baffle trapping 13% to 24% of exaust i have a straight pipe on mine with a baffle at a 10* angle 18in from the turbo and i can tell the difference between with and without
BOMBARDIER
Joined: Mar 2007
Posts: 12,854
Likes: 1,112
From: Illinois?
As I said.
This is another one of those controversial issues that have been proven on the Dyno's but straight pipes are cool so nobody will believe the results. Dyno's have shown a small power loss with straight pipes versus a good aftermarket exhaust. I can't tell you why myself. Most guy's say that diesel's don't require any back pressure but everything I've read and been told by professional dieseler's is that they like a minimal amount of back pressure. Were talkin 3 pounds and less of pressure.
BOMBARDIER
Joined: Mar 2007
Posts: 23,293
Likes: 1,322
From: North of You
not true dyno proven that you will build boost faster and your motor will run mode efficient at lower RPM with some kind of baffle trapping 13% to 24% of exaust i have a straight pipe on mine with a baffle at a 10* angle 18in from the turbo and i can tell the difference between with and without
I had a 3" straightpipe - hated it.
Went to a 4" with the muffler - its still too loud.
Diesel Enthusiast
Joined: Jul 2009
Posts: 379
Likes: 5
From: NM
I had my original exhaust on then I straight piped as soon as I bought the truck so I had 3 inch straight pipe. Just installed thursday 4 inch down pipe to 5 inch straight expandit exhaust and it made a notable difference and sounds great. My truck is only for work I don't drive it every day so I love the massive noise. Plus it spools faster and hits me 1-2 more psi boost I could theorize on it but I don't care it works great for me.
.... help mileage too went from 15.6 to 17.2
Diesel Wrench
Joined: Sep 2009
Posts: 585
Likes: 10
From: Louisville, KY
so does pipe size from the turbo back make a diff. in sound like makes it lower or higher pitched. i have the stock downpipe back to the back of the cab going into 4inch and then 5inch stacks. I like the low deep tone that some of the cummins have but mine sounds more high sounding than most would 4inch all the way back change anything
