faylur, your getting hung up on the rpms. a 4500rpm 8" will never see more then 2500ish with your power and torque...you don't have enough to make it go there... if you put a 10" 2500-3000 stall in your car it will not rev because again you don't have enough hp ftq to push that convertor to 2500-3000 it will be more like 1800rpms and with the extra weight the 10" will even slow it down more...