When do stock FPR's start to limit power
 

I'm in the process of putting a shopping list together for the venture up to 400bhp on my type r.

Already have the 6 speed box, v7 sti block, 800cc injectors and 340lph pump so I'll be shopping for a turbo, intercooler and other bits soon.

I've read that some people have gone past 400bhp on a stock fpr, others say you MUST fit an adjustble, so I'd like to know what people have on theirs. Is it possible to fit an aftermarket PFR after the stock one, like the old fse ones used to?? I'm not too clued up on wether theyre an add on or replacement.

Turbo is likely to be an MD and I may go with avcs heads to help spool. Brakes/suspension are already sorted.