expect to see 0.5-1.5 hp. it all depends on mod to get the most out of the pulleys. if you have a SOHC engine with light mods, don't even bother to put the pulleys on. its pointless to have it on. if you do plan on doing it, it's going to be a bitch. it will take a long time for you to do it. from what i heard, orthodox is better than AEM