The turbo your using may have alot to do with the peak rpm your car pulls too. Even with a stock location 30r style turbo (mine has a 2.5" inlet) my car really peaks out at around 7500 or so. If your still using the vf turbo then thats probably why the car peaks so quickly...a frien of mine around here with a swapped ver 8 bugeye wagon says the same thing...I think he had the twin scroll vf37 and he says it'll rev to 8k, but falls off quick at 6500.
hope that helps
Trey