For starters you could make an intake and get a bigger downpipe.Those are good flow mods that will help you get more out of the HV3.It is a worthy mod, you will like it. but honestly you really wont get 30hp unless you have a tune,rockers, and ported throttle body along with intake and exhaust and even then you're only getting a 30whp spike above 5k rpm. But youll prob make an honest 15whp.