Just for everyones information, boost pressure(psi) and horsepower have almost no relation. It is all about the turbos capability to flow(lbs of air per min.), that makes horsepower. Thats is why, for example, a Garrett gt28 and a Garrett gt42 do not make anywhere near the same power at 10 psi of boost. You do however need to run a certain amount of boost pressure in order to get to max air flow, but this all varies on engine mods, exhaust, and, of course, turbo size. I am not sure what size the stock T1100 turbo is, but that could be part of the reason why it doesn't make as much power as the Nytro at 13 psi. The Nytro also has a higher stock compression ratio and without a head spacer or low compression pistons will be more efficient at that low boost pressure of 13 psi.