I just put a #100 plate in my truck and have the wastegate line pinched, and I am hitting 35 psi on the gauge, what is a safe limit for my stock turbo?

 

You should be fine but that is somewhat close to the limits of the stock turbo. Some people say 38 is max,some say 35,but I have ran 38 on a stocker with no problems. Any more boost than that makes the turbo become inefficiant and your not making anymore power.