vettenovice

I have a stock '01 C5 MN^ except for Corsa exhaust. I am considering headers and an X-pipe. Before I ask for advise on manufacturers, can you guys answer a few questions?

1) I prefer to leave the stock cats in place to avoid emmission issues.

2) I prefer to leave the stock air intake in place.

3) Assuming stock cats and intake, what king of HP gains should I expect?

4) Pros/Cons of long tube vs. shorties?

Thanks!

Ragtop_Rob

I thought NJ had the OBDII emission testing like Maryland now?

c5freak

An engine is an air pump.
By installing headers, you are helping the engine get rid of its spent gases. That's good. But if you restrict the air intake by keeping the stock air box, you are partially defeating the purpose of the headers.
Also, if you are going to keep the stock cats, you are also defeating any good that the headers are doing.
My guess is that you may see some increase in hp but not much.
Forget the shortie headers. Get longtubes, cold air intake, aftermarket tail section, and high flow cats (or no cats at all).
You will then see about 25-30 rwhp increase with some tuning.

vettenovice

C5freak,

Thanks for the reply. Looks like I won't do the headers since I doubt high flow cats will pass NJ emmissions testing and it looks like there's no sense in spending $1800 for headers to only see under 10HP gain.

vettenuts

Based on what you are looking for, you may want to check out the Bellanger's. They are designed to keep the stock cats, are a Tri-Y design, make good low end power and use by a lot of autocross guys.

mdhmi

Do a $200 Blackwing intake and call it good.

Mark

RAFTRACER

TPIS and Kooks offer stock catalyst versions, there may be others. Yes there wil still be significant gains, but not as much if you would do the rest. Shortie headers are a waist of time and money. I have tested tri-y's, and yes they made reasonable low-end numbers but at the top end they were lack-luster at best (I haven't yet tested QTP's). Alot of top level racing teams have been using tri-y's , but they are not like the commonly available C5 tri-y's. Commonly available x-pipe 's way rearward in the system will calm down some noise and yield negligable power increase as in comparison to real x-pipe's. (but you would need to eliminate cats or move way rearward to use REAL x-pipe).

Buy some reasonable headers, you'll be happy

charlieb

I just added Bassani 1 3/4 LT headers and hi flo cats. Before and after dyno shows 10 rwhp gain w/o tune. Not the biggest bang for your hp buck, but the sound makes up for it, it's awesome. I'll go back for a tune after intake mods.