Will aftermarket headers affect how lean/rich the car runs?

 

nope. As far as i know it wont effect anything...i know if u are installing header/dp. When you start the car up for the first time u have to let it settle and let the wideband get use to the new air flow

 

--x2

 

let the wideband get used to the airflow? what?

and yes a high flow header and downpipe will lean the car out a little, my car went from 10.0 on the wideband to 10.9-11.0 AFR at wide open throttle

 

Wow, a whole point that seems like a lot, although the stock setup is pretty restrictive. Depending on what your running now op, if you go with a new exhaust setup you will run a little leaner, however it doesn't appear that your tuned so don't worry about it. The gm stage 2 tunes run EXTREMELY rich so the leaner you can get them the better.

 

what i ment to agree with was the stock stage two tune is rich even with a 2.9 and cti header three inch downpipe-back i was still running 10 flats

 

what i ment was (this is what i was told because ill be installing new header/dp/exhaust in a few weeks)...is that when the car starts up for the first time the a/f is abit jumpy so u have to let it idle abit then it will calm down.

 

A smaller pulley will not necessarily lean you out, your maf will read all the new airflow coming in and proceed to dumping more fuel in to keep you at the commanded afr.

 

not always
just depends on how the maf scaling is setup

 

the op is proly the coolest guy u will ever meet