I'm going to be running 7psi on my stock block with 187k miles. Only tuned to 3psi so far.
Some people have managed to push a stock block over 500hp with a good tune.Someone i know hit 440hp @ 22psi, so if your going for 30 that's gonna be way up there.
I would start by checking out KA-t.org as well as reading their DOHC Turbo thread. Here's the link.
http://www.ka-t.org/forums/viewtopic.php?t=6263
Then to speak to someone who has high horsepower KA-T experience, it might be good to get in touch with the guys at AMSperformance.