Automatic or manual?
It also sounds to me like you are having belt slip, thus causing the lower boost number.
Of course the catless mid pipe is probably also a contributing factor.
And what were the A/F numbers running?
The belt was slipping before and I was only seeing 5psi. I changed the tensioner and there is no slipping at 6.5 psi. I went ahead and ordered a 3.70 pulley. I want more boost. I'm a manual by the way. Sent from AutoGuide.com Free App