I have a Y8 with the GReddy td04h 15g kit and a Zex Street/Strip Cam for the y8.

My problem is when I hit 4800 rpm in any gear boost drops atleast 2psi and another .5-1psi at 5500 rpm. I hook an MBC up to it and turned the boost up to roughly 10psi to see if it would still do it and of course it did. I also removed the MBC and adjusted the wastegate arm and I really didn't get any change in boost, it just caused the turbo to spool slower.

What is the deal with this?

Is the turbo too small and it can't spool at higher rpms?
Is there too much overlap with the cam?
Do I have a boost leak?

TIA

 

you just answered your own question. the greddy turbo is quite small and will not flow that well at higher RPMs. you will see a drop in boost pressure.. get a profec-B or any other boost controller with PID GAIN features.

 

I figured I probably new what the problem was but I just wanted to get some other opinions.