Let’s begin with what boost creep is – mostly taken right from Garrets website btw.
Boost creep is a condition of rising boost levels past what the predetermined level has been set at. Boost creep is caused by a fully opened Wastegates not being able to flow enough exhaust to bypass the exhaust turbine via the Wastegates itself. For example, if your boost is set to 12psi, and you go into full boost, you will see a quick rise to 12 or 13psi, but as the rpm's increase, the boost levels also increase beyond what the boost controller is calling for. Boost creep is typically more pronounced at higher rpm's since there is more exhaust flow present for the Wastegates to bypass. Boost creep is most commonly observed in areas that have very low ambient temperatures as well as low elevation – sea level.
Effective methods of avoiding or eliminating boost creep include porting the internal Wastegates opening to allow more airflow out of the turbine, or to use an external Wastegates. Not having a free flow (or catless) exhaust system can help prevent boost creep.
Why do we bring this up?
We are tuning more and more of these cars and finding that people who have free flow cat-less exhaust are experiencing boost creep like we have never seen before on any other platform. Especially now that it's getting colder out.
To be clear, we are not talking about boost spikes on gear shifts.
We have always found that as people started adding aftermarket pipes - muffler delete or lower downpipes that the boost control was a lot more touchy. But it was something that could always been tuned when you had proper control - EcuTek.
What should I do - How do I prevent boost creep?
Keeping your emissions equipment on the car really helps.