I got out and drove my car tonight and it was the first time I've driven it in sub-freezing temperatures. The boost went up to 11psi in 3rd up a hill. All I have is a cat-back. I didn't think it'd creep with only a catback.. what's going on, and how do I fix it?

 

Notes:

1. it's been running 9psi since i got the bugs worked out

2. by "how do i fix it"... i mean how do i fix it easily and cheaply?

 

The only fix to boost creep is to add more restriction to the intake/exhuast system (putting your stock catback on again) or porting the wastegate larger.