I've cranked down my hallman rbx MBC all the way, yet the boost level remains at ~9 PSI -- which I know is the wastegate boost for the TD05. I've got the Hallman hooked up the same way as I had with the VF11 (and it worked there). Side nipple to the wastegate, end nipple to the turbo compressor. Autometer boost gauge is teed off the #1 runner and holds steady whatever the boost is (unlike others who describe constant shaking).
Searching the forum, there have been several other users who have td05 wastegate boost issue -- none really resolved it.
Reading in the hallman manual, one finds the following:
1. Do you think I need to switch out the heavier spring?If you purchased the RX option your kit came with a ceramic ball and two different springs, one light and one heavy. The light spring came already installed in the controller and the heavy spring is included in a marked bag. The light spring is good for adding up to 5 pounds of boost over the stock boost level. If your stock level is 10 psi then the light spring could add up to an additional 5 psi for a total of 15 pounds of boost. The heavy spring can add much more than that. The light spring will allow you to adjust boost in very small increments.
2. I don't believe I have any leaks (well nothing obvious sounds of rushing air during WOT) in the intake/tmic tubing. One can look over my TD05 install pics here. What else would cause this problem?