Quote Originally Posted by Fast355 View Post
It is mostly stock other than the cam, tuned 0411 pcm, LT1 exhaust manifolds, high flow cats, and magnaflow muffler...Oh it has an e-fan conversion and under drive pulleys on it too.

OBDI is not the problem, the tuner is. I have had two different GM OBDI vehicles over 340 RWHP.

To make 300 RWHP with an GM Automatic 2wd 1/2 ton driveline you need about 375 HP at the flywheel and some good weather.
I must be leaving a lot on the table still. My 357 is 9.7:1 with Vortecs and the 204/207 .447/.459 LT1 cam, long tubes and Eddy performer intake. The truck is 5000lbs, but it feels so slow. And the tune is fairly close according to my datalogs. I've been dissappointed with the power since day 1, especially given the animal the Camaro's 355 was.