just want to make sure i have this correct. bigger is better. smaller is bad as it will burn up the turbo and motor from to much egt. all of this from some trucks at work with exaust pipe rusted out and repaired. and it was not done correctly if you ask me. i could be wrong tho.
It depends. The stock 3" systems with very restrictive mufflers AND a resonator flow enough for a stock Ram CUmmins. Does it flow much better with a nice 4" or 5" system, heck yeah, but it's not needed at stock or slightly above stock power levels. 5" actually hurts power some unless you are making 650HP or more....
I fully agree. I have heard of some guys with the 6.5s wanting the 3.5" exhaust off of the new Duramax trucks to upgrade. But the 5" exhaust on a Duramax actually cuts down on power until you are creating enough power to need that large of an exhaust. Keep these #'s in mind for exhausts 3.5" has a cross section of roughly 9.621 sq in 4" has a cross section of roughly 12.566 sq in 5" has a cross section of roughly 19.635 sq in These calculations are assuming that the size called out is the inside diameter. So a 5" exhaust is roughly twice the size of a 3.5" and 64% larger than a 4". You got to be pushin serious power for a 5" to be benificial.
Yep, the only thing 5" does really is add bling and make it sound like an N14.imp: Oh, and make it drone harder...
