mine was tuned at 245rwkw no FPR or other mods, standard RB25 injectors, and I've seen it hit max duty on my display several times at WOT in 4th, so I turned the boost down, however, everyone I've spoken to (ie mechanics) has said that adjustable FPR aren't worth bothering about and to just get new injectors / retune.
Wouldn't that be safer than trying to stretch the limits of your current injectors?