Well, I didn't know BBK made an X-pipe. But is it with cats, or off road? Since the stock cat back is actually pretty good, the after market mufflers give little at best. The CAI is a throw up... But since the JET has made a significant difference... I won't guess but, here:
Stock 99-2000 GTs typically dyno at about 225-230ish rwhp. If you figure a 15% loss for a manual drive train then that's roughly 265-270 SAE net hp. Some what better then their rated numbers. Some do better, so do worse, but with your bolt ons I would guestimate 280 hp???
The only real way is to run it on a track and look at the ET and trap MPH. From there you taking into account temp and humidity you can get a pretty good idea of hp.
------------------
AIM: Some97Snake
|