My family and i have a 1967 gto and a 1968 firebird both of which are sportsman/pro bracket cars. My brother has been looking into running the firebird in stock because it other guys are doing it and they are competitive with their combination. I was just looking for laughs at what class the 1967 gto would fall into. I saw that with the 335 hp combo it would naturally be be a g/sa. Why has nobody done the gto with this hp combination before? I don't think it would be too hard to get it to run under the 12.00 index. Are the other cars running in g and h stock auto just at a much better advantage than the gto would be? When comparing it to the 325 hp firebird combination it doesn't sound too bad. Both are 400 ci. rated within 10 hp of each other. Cam lifts for pontiac are all about the same at .420 The only difference I can see would be the weight of the car (which is why its a slower class than the firebird) and the heads. The firebird would use the 16 casting which I've heard is the best pontiac D-port casting. I think I've come to the conclusion that the gto could use the 670 head which is another good head and it's closed chamber. I know the firebird is a good combo, I'm wanting to know why not the GTO. All answers are appreciated thankyou.