You arent going to make a reliable sr with 250rwkw without opening the engine.... mid 12's....take at look at the disco potato set up. stock engine, new tune and turbo...was running mid to low 12's i think.
Mr bro is pushing 230HP out of his stock sr engine, on 1 bar, and a chip and tune.
and i am pushing very close to that out of my stock rb, but my old turbo wont hold boost top end.
Rsktker: If you want it to be reliable on 250rwkw then just spend money right, 250rwkw is still pretty large out of the 4 cyc....and depends if you want it for response or what. there are so many ways to set up the engine.
but it is stupid to transfer an rb into a 180 unless you to put an rb25 into it and produce HP. sr is a lighter, newer technology engine, better torque curve then an rb i find.