the 5th gen responds decently to bolt ons. But even with a couple bolt ons, you won't be over 200whp. Stock h22's can handle anywhere up to 8-9 psi, but the key is a good tune by a knowledgeable tuner. I personally wouldn't go past 7-8 psi on the stock engine, but some people treat boost like crack-rock, and they NEED MORE!
Some people just can't grasp the concept that: stock motor + lots of boost it wasn't meant for = BOOM!
Tuning is the MOST IMPORTANT part of going turbo on a stock motor, or even a built one. It needs to be tuned.