i just bought a 2002 f12x with a turbo when i first got it, it would run at 6100 rpm and run 61mph but the longer i ran it the lower the rpm got. now it only goes to 5500 rpm before the rev limit kicks in and 51mph at 3/4th throttle it just seem like the rev limit kicks in so fast not even at full throttle. any clues on what i can do to make it run better???