Hrm completely stock? I'd consider my 2g mild (although I do have the supporting mods on the shelf)
. I've got a ported FP B28 running @ 17psi on the stock fuel, stock IC, unported O2 housing & e.manifold, upgraded exhaust and upper ic pipes w/ type s bov. You will have to do something about the fuel if you plan to go beyond 15psi safely. You can either listen to these "OG's" or learn the hard way like me. Fuel cut is not a fun thing to experience. Play it safe @ around 15 and you should be ok until you get more support. It's a "fun" turbo, if you aren't looking for an outrageous HP number.