What is the stock exhaust diameter? I have an injen exhaust and was wondering how much power gains to expect with a megan mid and s pipe? How about if I add headers?

 

exhaust with mid and s-pipe...around 6-8whp
with header...another 6-8whp...maybe

 

best thing to do would be to add engine management to all of that and get it tuned...

 

If you get engine management you would probly have to get a afr gauge too. I have i/h/e and i wanted to get an engine management like aem or something, but it would cost alot for those few extra hp there is to gain. Maybe around 800 to 1000 for the whole setup

 

I looked on google and didnt find much about engine management system... how does that work and what does it actually manage... like my compression ratio and internals?

 

Mostly it enables you to adjust the timeing and the fuel injectors.

 

The gains you get with an exhaust, header, and intake are pretty standard across the board. I have to be honest. I don't think it matters from one exhaust to another. With some exhausts, you have to be careful though. I made the mistake of getting a cheap exhaust system first, I had no back pressure. Thus, no torque. My car would scream on the highway, but I had no dig from a light. I just put my stock back on. Oh well.

 

Just to add, the Injen exhaust is awsome. I wasn't bashing your exhaust, just throwing my to bits out there...........yeah. That injen should set you pretty straight. They sound awsome too!!!

 

The reason I am asking this question is because I plan on S/C my car. If I put the money into the S/C, I am wondering if it would be worth it to add the headers, s pipe, and mid pipe to my injen exhaust.

 

Either way, the supercharger is going to be compressing that air into your motor, so the more air you bring in, the more you need to exhaust, so I personally would say go for the full exhaust set up. Technically, you don't "need" it, but it would help. I don't have much experience with the S/C, but I do know motors. I am sure someone else can post more info regarding the S/C.

 

dont add headers if you want your warranty!

 

ABSOLUTELY CORRECT!!!! Keep that in mind if you are worried about warranty issues.