Whether or not you need to change the FPR depends on two things
1) your fuel pump, and whether or not it flows too much for the FPR to bypass to keep the pressure down
2) you need a higher base fuel pressure (not enough injector for your power requirements)
You don't meet either of these criteria, so you're fine with the stock one. That is assuming your 800cc injectors can keep up, but even if they can't you won't be able to bump up the pressure much at all before hitting the limits of the fuel pump, so it doesn't really matter.