Not to keep bugging you, but what injectors were you using? Would happen to have duty cycle information? Any EGT or AF data?

The customer in question is running forged internals, so heavier boost shouldn't be a problem, but I'm still stupified. I think he might be running STi injectors though...if that's the case, and I advised against the 550cc/tried to sell him 800cc, I think I'll have my answer.

IHI built turbos are limited due to their compact size. They're essentially OEM pieces (PEs not included, of course), so it's tough to expect too much. I used a 34 on my car because I was gunning for ~300whp, daily driveable on STi injectors. I also wanted to minimize boost lag, considering I was adding a FMIC...but I digress.