4 bar FPR will not increase performance in any kind of way.
Revo use it in their stage 2 setup merely for safety purposes, but jabbasport and CC for instance do not require it. On the LCR setup anyway.
You have smaller injectors in the LC so you wont get the same flow as the LCR on 3 bar.
LCR on 3 bar is approx 386cc injectors and when a 4 bar is used it makes them around the 440cc mark.
I have no idea though what 3 bar and 4 bar does to LC injectors