Pretty impressive. But a few thoughts, have you measured backpressure during a run? It seems it should make more than that on 17 pounds. You might need a little larger ar and maybe a larger turbo all together. For reference my j35 Honda (not a direct comparison I know) made just over 560 at the crank on 16psi with a 68mm gt35 before we went to e85 and really turned the wick up. I ran out of turbo pretty quick.
