· Premium Member
I had a 7psi spring on my T04 kit that I had and ran 18psi all the time. I even turned it up past 20 a few times too and had no problems getting there. If you have a GOOD electronic boost controller and hook it up the right way, you can actually force it closed with the pressure until the boost controller decides to slap it open. Hence, the two ports on the wastegate. That's how I always made mine work. I never needed a bigger spring.