How much boost can a 1.8T handle on stock internals? I wanna go about 16PSI but im not sure if its safe.

 

It can probably handle 15 tops safely, however you will not make any power doing so. I have dyno'd a 1.8t until it blew up, we took the tubo up to 30psi before it sploded, power actually started going down. The reason you ask? Simply put, heat. The more PSI the more heat, after you have enough heat in that turbo it loses power, and eventually you will damage the compressor or blow the whole turbo. If you are seriously considering turning up your turbo do some research, get a bigger intercooler for starters.