ive just purchased a S5 convertible non-turbo. i need to find parts to rebuild a turbo motor.i need to know if there is ne difference in the motors for this vehicles year an witch one is the best to build for maximum power? are the rotors in the turbo motor forged? can you buy new rotors to get different compresion ratios? if so where? i am new to the wankel engine so i have a million questions but these will get me started.