Is the gm honed exhaust manifold a good buy. i do know with going with one you keep your warnity but well you see any type of performance increase. it says that it is a increase of 30 cfm flow. i was wondering what kind of cfm increases would be found on other after market headers. Also if i do pick up one i would like to go with a dp but if i do that do i void my warnity. it is important to me to keep my warnity but make my car as fast as i can. any help please. As my car sits now i have gm stage 2 cai ca heat exchanger ark cat back dual pass intercooler. and some others.

 

after market headers will net a lot more gains than the GM stuff.