the kit improves every where. the average gain is 7-10% depending on your altitude. i was dynoed at sand mntn. in nevada at 46 hp. and the only thing im still running from yhe kit is the cam and vents, thats 9 hp over stock for where i live in cali. (smog state) choked. thats about 25%. new exaust,filter, is where its at. use the hrc needle and just buy a few different main jets for fine tuning for elevation. dont bother with a jet kit unless it comes with a new pipe.