The stock Corvette and Viper in GT5: P sound weak too - I don't think whether they're tuned or not is the point. I know the sounds have improved, but they're way off most PC sims and Forza, Need For Speed etc. It can't be that GT5: P's are realistic, and most other race games suggested above are not. The engine sounds don't even change under load. Sound the same on light throttle, in neutral or when the foot is floored at mid revs whilst driving up an incline.