FPR's are normally used as a "band-aid fix" for lean running engine, however, if you aren't useing an aftermarket ecu or boost, you may find that you can gain power by LOWERING your fuel pressure with a stock ECU since they typically run a little rich [very little, but it's there], but again, they really should only be used as a tool to make sure your fuel pressure stays where you want when you start upgrading your fuel system.