[89IROC&RS]

too many variables, how do you know his car was stock? also, the car downshifts to keep you in the gasmileage zone, not really performance. when you put in your rear gears did you calibrate the speedometer???? check to see if you have a cable driven speedo, or an electric, if its cable, you have to change the gears on the drive unit to make them read correctly, if you have an electric, you have to find a programmer to change the variables in the computer. email or call hypertech they are the people to ask about that problem. but i bet that calibration because the computer is not seeing what it is supposed to see as far as a corrilation between the speedo and the tach, is throwing something off as its trying to compensate for the difference. fix the calibration and everything will probly sort its self out.