Sounds like the G8 is a whole different beast when it comes to tuning. I haven't had the time or money to play with my G8 much (wedding in 6 months), but when I was playing with my Grand Prix, I definitely hit the rev limiter too fast. I had a cam in her, and I had to command it to shift quite a bit before the actual rev limiter thanks to it reving up really fast, plus I bumped it (rev limiter) up like an additional 100RPM's on top of what I already did.

I honestly have a problem right now with my fairly stock GT pegging the rev limiter in 1st gear and sometime 2nd.... buuut I think that's an entirely different problem.

Sounds great otherwise! I'd love to cam my baby!