If your car is stock I wouldn't recommend you using the 1 7/8" as you're not making enough power. Usually the 1 7/8" are for big cube motors or people doing a H/C package with other goodies i.e. FAST intake, 90 mm TB, gears etc. Just my $.0202Redzo6 said:Whats the difference in these vs non race headers? Would they be ok to put on a stock z? And do you have the offroad Xpipe?