You could always install a thicker headgasket and decompress the engine, but if he's only going to be running 7psi max, then I wouldn't bother.
Already covered by Roy, restrictive exhaust is a bad idea... Have it as free flowing as you can get it.
As for the idea of a restrictive intercooler, what purpose does that serve? So your turbo will spool upto blowing 7psi of pressure, but the intercooler creates a 4psi drop, so you're only getting 4psi at the intake plenum... What does that do? Well your boost controller is asking for 7psi at the intake plenum, so now your turbo has to blow 11psi to make 7psi at the intake plenum. Restrictive intercooler doesn't sound like too great an idea now does it