Wow. what's the "safe" boost limit? How much do you need to make 350-380? On previous setups when I used to tune myself, we always ran more boost less timing to keep the stock motors together and heads from lifting. 35psi and less timing on a given setup almost always made about the same and safer power than 30psi and more timing. I stopped tuning myself when I got into Audi's and canned safe tunes.
See that's the dilemma, a lot of people desire big power without lag, so people end up spinning their turbo where it shouldn't go and either the turbo blows up or the engine does.
Back to the question, you can make just shy of 300whp on 91 with wmi @25psi, and just over 300whp on E30M. Imo you should only run as much boost as the cylinder head can efficiently take in which is right around 26-28psi I believe. Anymore and you're cramming boost for minimal DANGEROUS gains. The head on this engine are actually horrible cfm wise everything from Japan flows better.
Even the worst D16 series head from the base civic outflows these heads and the best casting from the D16 series outflows the ported head on our engine from mountune....
So instead of effectively scavenging and consuming the extra boost you end up pressuring the head once you move out the threshold and it obviously this effect increases with boost pressure...
This platform needs a new head casting BAD imo, something that mimics the Honda K series in design. Ford put ZERO effort into the port design of the head for obvious reasons.