If the intercooler pipe looks like swiss cheese, then Id say you would notice the car running funny. I guess if you wanna lug the air compressor around, and bother the seller to take his car apart so you can hose it down with soapy water....all Im saying is a couple boost leaks are gonna be the last of your worries when buying a used car.

Compression test on the other hand, thats a great idea and worth the time to test IMO.