Exhaust Question, matching dp/piping/muffler size Options

[elvasoshexai]

ok... i have some questions that sounds really dumb... but i just wanted some opinions

at first.. i was planning on doing 2.5" exhaust from turbo back... cause 3" seemed unnecessary for my goals (my goal is about 200-220whp...) and i thought that using the same size piping all the way back would be better too since maybe the gases would flow smoother?.?.?.

1. then i was looking around and 3" DPs basically cost the same as a 2.5" DP... and it seems that from tests done by KOR and Berk... with a 3" dp you get faster spool and a couple more horses if all you replace is ur 2.5" DP w/ a 3" DP and nothing else...however... all these tests were for 3sgtes... i'm not sure if our 5sfe's would benefit from one since we are already pushing our engines near the edge

2. i also wanted a magnaflow muffler... but they only have 2 models that i liked... and neither had a 2.5" inlet... one had 3" inlet w/ 3" internal core and the other is a 2.25" inlet w/ 2.5" internal core...

i dunno if my thinking is flawed.. but like... if u go from 3"DP to 2.5" piping.. ur pushing more air into a smaller area and so... it would hv mroe restrictions.. then ur goign from 2.5" back to 3" but now the gases are coming out from a smaller opening and so it's not as smooth... so......... if i am using 2.5" piping from after DP to before Muffler... i was just wondering which would be a better idea:

-2.5" or 3" DP? (especially those with 5sfte's w/ a 3".. would u do it again or just use 2.5")
and
-weld a muffler w/ 3" inlet and 3" internal core or remove 2.25" inlet and weld to muffler so it'sstraight 2.5" all the way bacK?

i would think the muffler part doesn't make much difference at all... but well.. couldn't find an answer on it...

This post has been edited by elvasoshexai: Oct 6, 2006 - 2:45 PM

[x_itchy_b_x]

I enjoyed my 2.5" on the 5sfte with matching downpipe, The FE head limits alot of flow thats where 3sgte makes the power and flow. well any motor for that matter is the head. if you plan on running aftermarket camshafts/valves that allow more air flow then you should go 3" but like manny said. 2.5" is adequate for a moderate 5sfte setup.