Whenever i accelerate in gear (2nd and up), my rpm's go down first and then go back up. Is this due to my clutch slipping or is there another problem? I know my clutch is probably pretty worn out since it's still the original clutch at 80k miles. If it is the clutch, do you guys recommend just switching to an M3 clutch since i'm going to be looking at some major power mods in the future?