If a P&P is done correctly, it can add loads of power and response. How would adding stock compression forged pistons make an engine detonate?! I did remove the butterflies and it didn't do anything noticeable, but its comforting knowing theres nothing clogging your lower plenums air passage. By stock he means stock bottom end, metal head gasket, stock head, upgraded injectors (i hope), upgraded fuel pump, and dual electrics to help keep it all cool.