i have a sc300 with a stock twin turbo 1jz with a manual boost controller, the car is running 15psi n i what to bring it to 12psi but my boost controller is at the max low, ideas?

 

Take off the manual boost controller and hook up a vacuum line straight to the wastegate, and run the car, if it stays at 15# that means it has a 15# spring in the wastegate. Which means that's the lowest you can run.

 

its the stock twin internal wastegates, I think the springs are 10

 

If it's stock and it's doing 15 with the manual boost controller all the way closed, you have a vaccum leak somewhere from where you get your vacuum signal all the way to the wastegate. or malfunctioning boost controller. That's why I said to eliminate the manual boost controller completely first to check stock boost.

 

remove the MBC and reinstall the lines. It should be fine after that..