I have Gt35rs turbo, raduim air to air innercooler, custom piping to innercooler. Upgraded clutch, new fuel pump, larger injectors. Alot more to list but not needed for my question. I feel I should make more with those add-ons. Just don't want to buy motor just yet. 12k on the clock now.
I think that at 11psi you're pushing about the top range of what people run on the stock internals, but it sounds like your car should be putting down a few more horsepower.
Keep in mind that dynos are different, sometimes by 10+% so 250 on your dyno might be 270 on someone else's, and 270 seems about right for 11psi.
I've found people on here saying they were making 275 or so with 11psi on stock internals with pump gas, and I think the Radium people got a GT2860RS @ 11psi on a stock engine to 300hp or so on race gas.
Lots more variables than just absolute maximum PSI when it comes to how much power the car will put down... 11psi of maximum boost doesn't do much if you can't flow enough air to maintain it through the powerband, plus you need to keep intake temps down so the car doesn't have to pull timing, and that's all assuming your tune is ideal which is difficult on these cars (between the cam switchover and variable valve timing there's a lot to do on top of the norm).
I'd start by logging spark, AFR, boost, and intake temps and see if anything looks fishy.