they do offer a correction feature but if you have the number set to 1 its supposed to give you whp. the way you get the horsepower from the flywheel is to divide the dealer rated horsepower by the hp you get when its set at 1 and then change the 1 to that number so for example lets just say i was really putting down 136 hp and the engine is rated at 140. I would change the hp correction number from 1.00 to 1.03 and if i did the identical run it would give me 140 hp instead of 136. Follow me?