[btwilson86]

This was sent in a PM to dannys35, but thought I'd post it here so that anyone else having a similar problem will be able to get some info from this thread:

On the front side of the turbo, towards the bottom of it there should be a round disk with a vacuum line coming out of it. This is your wastegate actuator (this controls when the wastegate opens, which regulates how high or low your turbo will spool). When routed properly, this vacuum line will have the other end of it connect to an intake hose that receives boost (don't remember where the factory one is, but it's after the turbo). What you want to do is put your mbc (manual boost controller) in this vacuum line. This way the mbc can restrict the flow of the boosted air to the wastegate actuator, causing it to open less and later, resulting in higher boost.

With that said, you should definitely check for any vacuum leaks or degrading hose couplers, etc. that can result in leaking boost. Any boost leak will cause a higher work load on the turbo, which could drastically shorten it's life. This is also important because as I understand it 12 psi is near the upper limits of the stock fuel delivery system, which means you'll start running lean and hit fuel cut