I'm with MisterX here...
There are two things that all the engines that have lasted 30,000+ miles making over 400hp have in common: lots of fuel and relatively low boost (17psi or less). Does it make total sense? No, boost to some degree shouldn't matter (as God has pointed out numerous times) with proper tuning, and Cobb has been getting 250 whp out of their RT-spec kit without any fuel upgrades and doing so very reliably for quite some time. I don't know, all I can say is this:
I want a 100k mile motor, so even with a mild turbo upgrade (260-270 whp) I will be doing upgraded injectors, rails, and pump, and I won't push more than 17 psi peak. Conservative? Yes. Overkill? Certainly. Peace of mind? Yup, that too. Compared to a new motor, fuel upgrades and small sacrifices in boost are cheap insurance.