If aiming for 310-320bhp, what size injectors are needed? Seen a set of 500cc for sale (from a hawk STi), will these be suitable? Or am i better off with pinks?

 

I think the STI injectors are 550's mate. These will be fine for what you need.
IIRC standard newage WRX ones are 380? There are also 440's knocking about.
I don't know too much about em but I know there are side and top feed, and you'll need ones suitable for your motor.

 

Pink Injectors are def 550's, but according to the guy selling the 500's, they were removed from a Hawkeye STI. They are the Denso ones for sale on here, just wondered if I could use these instead of 550's which I think are from the bug and blob STI's. My thought is that if removed from a Hawk STI, then they would be newer with less miles on.

 

Don't see why not - I would imagine 500's would be good enough for what you're shooting for, but ask a capable mapper for a definite answer.

 

Got STI Pinks this week so just got to save for a VF34/5 now, plus NGK PFR7Bs.

Looking to get new gaskets for the uppipe, seen them at scoobyclinic on the link below, anyone know anywhere else that sells them and is this reasonable price? (header to uppipe £10.50 and uppipe to turbo £11.50). Uppipe is one from enginemapper.

http://www.scoobyclinic.com/products_exhausts.htm

 

Or just buy them from your dealer - they'll all use genuine parts.