I'm running 25 psi and 28.5 psi using the LO/HI modes of my Greddy Profec B Spec II. No problems.

 

Was told 25 psi is safe maximum level.
Only know from research, stock is 20 psi tapering down to 17 at approx 5500 rpms. Again, I'm no expert but huge power gain from that 5lbs of boost.
They mentioned the seals, not so much the turbo itself.
Personally I'm greedy in the power dept, always want more.
But I have learned safe is better than being able to push it a little harder only to destroy engine/turbo or both.

Would love to build the block & get a get a gt35r & pump that sucker up to blast.

Guy in my area is doing a subie pushing 45+ psi.
It's worked up the ying yang, but I'm jealous.

Car is quick at 25, I dream of 40-50 psi on a built block.

Then get to terrorize all the ls1 & 5.0s as an appetizer.

Search you tube for rb30 @ 50 psi, that thing is a monster.

http://youtu.be/ieVDfnUKN9s

 

I just recently had the car tuned through RRE and I am spiking 28 psi, and holding 25.5 psi until redline. It looks like based off everyone else's comments a X Stock turbo tuned spike 28-30 psi, and hold 24-26 psi until redline with basic supporting mods on 91 octane will usually yield 340-360 hp, and 350-370 lbft.

as far as mods go, my 2011 GSR has an Injen Intake + UICP, GrimmSpeed 3-Port Boost Controller, and Ultimate Racing Turbo Back Exhaust.

 

hi just curious because my SES pops up when i hit 27boost

 

Am tuned at exactly 26.5 steady boost no tampering down just stays at 26.5 through out the revs. no issues running that for almost 2 years. Tune by eric at kosmic motorsports