The SRT-4 guys have found that the clamps on the SRT-4 that connects the hoses to the boost circuit (turbo to intercooler, intercooler to throttle body, etc.) are almost all loose. They came up with a leak tester that mounts to the cold side of the turbo. Air is pushed into the system and someone watches the boost gauge as to how much pressure it holds or looses. Most of the time only the clamps need to be retightened. But many times vacuum hoses and even the stock PCV valve leaks under boost.
I have done a boost leak check on my car and had very many boost leaks that I fixed when I first got the car. But I read a thread on installing a check valve inline between the PCV valve and the throttle body (on SRT-4's) that will help stop the PCV valve from leaking under boost. I installed check valve yesterday and noticed great low and midrange torque improvement. Holds boost longer and more consistently through gears at WOT.
Have any of your done this or even considered doing a leak check on your boost circuits to look for boost leaks. There may be hidden potential for performance by checking for leaks. FYI.