[AlexBp]

sounds like youve fitted lower compression pistons saying they have cavaties??

therefor the as a naturally aspirated engine it wont perform aswell as they generally use a higher compression ratio

if so then a turbo is about your only option if you want to keep them
a turbo setup isnt cheap and an oil cooler would be needed but so would an intercooler some form of better injection (wether it be a 5th injector and mf2 or standalone and bigger cc injectors)

you could keep the ph3s but returning to the standard exhaust camshaft may be to your advantage