Ive got a HKS 2530 (T3 flange) on mine, i need to get the computer replaced, or rechipped, because if i run over 12psi the AFM maxes out, but on 12psi in my RB20 i put out 212rwkw (280rwhp i think). it bolts straight onto the existing manifold and dump pipe, but you will have to make new oil and water lines for it. but thats not too hard, i went for braided lines, which can get expensive.
i would recomend this turbo to anyone with an RB20 who wants a perfect street car. you dont loose alot of bottom end, but get alot of mid and top end power gains.