fpr = fuel pressure regulator
to get past 14.7 you need to either get an aftermarket ecu or get a fuel cut defender (fcd)
if you install a fcd make sure you get the fpr and bigger injectors in there and some sort of fuel controller to help you tune it... wack her on a dyno
you won't really notice a difference with the bigger injectors at that boost but as you start raising it you will not need to upgrade as you already have hehe
happy modding