It's hard to answer that one without either sounding arrogant or clueless...
But seriously, yes, that's about what I was expecting. There's no major bottlenecks in the hardware, and I'll never claim the turbo was being worked hard at 6psi. I expect that @
nix will hit the limits of the current exhaust housing on the turbo at 16~18psi, though it may stretch a bit further due to the e70~e85.
The turbo, as mentioned before, is a hybrid 18g. That's a turbo 2.5-liter WRX's and STI's upgrade to from the stock turbocharger. Key to the performance was simply sizing the hotside for the smaller motor so response didn't suffer while keeping that power going till 7K. The trade-off is that it likely won't breath that well above 8000rpm, that'll require a bigger hotside.
Our head engineer Terry has been turbocharging n/a's for 39+ years, he's pretty damned good at building out the right turbo for an application.