Go check this out.... It might give you some idea's, also if you email the guy, he might be able to answer a few questions since he's been through it...
http://www.msvorinich.itgo.com/
The guy in the webpage built a junked four cylinder turbo mustang from the ground up using mostly junkyard, home made and basically cheap parts.. He's currently running at 25psi but wants to go to 30+psi... Pretty impressive what he's done.. Go the the tour section and you can see the build from day one...
He built a massive 3 core intercooler by combining and welding three volvo intercoolers together... He states that the pipe before the intercooler is hot while the pipe after the intercooler going into the intake is chilled. Thats why he is able to run at such high boost on basically a stock engine without blowing the thing up.