220rwkw?
for the $5K you have to spend, you could make a reliable 250rwkw out of the RB20.
without the hassles of rego paper work, engine swap, being off the road for ages etc.
to make 220rwkw out of an RB25 you are going to need upgraded....
intercooler, fuel pump, afm, injectors, turbo, exhaust, ecu, tune
now, if you buy the above parts for the RB20 you already have, you will still make over 220rwkw and not have to fork out for the purchase of RB25, gearbox, tailshaft, engine swap costs.
If your goal was on the crazy side of 250rwkw, i'd understand the need for more capacity.
just a thought mate.
I think spending the cash on the rb20 will yeald good results for less money.
have a look in to the RB20 dyno results thread in the forced induction section to see what mods make what power on peoples cars.