Garrett just released a turbo upgrade for the SR20 rated at 450+hp. The GT3071R....and it bolts onto the Greddy manifold. Don't know about clearance or downpipe issues, so it might not fit, but if it does...OH YEAH!

http://www.turbobygarrett.com/turbob...30/GT3071R.htm

I might consider giving it a try later on this year...with a built motor, of course!