Quickest out of the box for that money is probably the STi Type R and they have relatively strong engines provided they are looked after.
For bang for your buck, i'd have a Type R over the P1 all day long. They don't suffer as badly from the air flow meter problems and they're a damn sight cheaper.
A P1 is up there with EVO 6 Tommi for being the most over-priced Jap car out there.
Yeah, P1 has the Prodrive goodies, but these can also be fitted as options to UK Turbos.
I'm selling my STi Type R due to not getting to use it as I'd like too. It's just used for going back and forward to work at the mo.
RA's with closed-deck red-tops are just as good as the Type R in many ways, but the 4 doors are too common IMO.
2 Door Scoobs look so much better too.
Good luck with whatever you decide to do.
JK