if only P&P i would say +-3hp
its difficult to raise hp on NA based engines if u only do 1 thing
but its kinda rewarding when ur done doing up a NA engine...just sharing my experience B)
wah???only 1?burn more than $500 and gain 1 hp?more la i think..maybe depend on the workshop la..if they do it properly..nice la and increases hp..if not..maybe not much la.. ;)