I'm going to go look at a 2008 Grand Prix, non-supercharged either tomorrow or Friday. if I end up getting it, I would like to do some tuning on it. On Overkill's website, he says gains of 10 hp can be had if 91 octane fuel is used. I was wondering if that is because there is less kr and more timing advance can be used. Is there much of the 97-03 tune that is similar on the 04+ cars?