i don't think you'll make it on a standard t3 from an rst, could be done on a cossie t3 though.
will need remapping and what injectors are you using?
i'm assuming the pistons are standard with using a decomp plate and as such i wouldn't want to push much through it.
but 15psi would probably get you there or very close, just get a bigger housing fitted e.g. 0.48 exhaust.