I have a great brass boost controller that I bought online for about $25 (I forgot exactly how much). It sits inline between the wastegate and turbo and acts as a secondary spring that you can adjust to specify exactly how much boost you want. I have a VDO boost gauge permanently installed in my car and the boost cranked up to 14psi. When I get home from vacation, I will post the website address for that boost controller. A few others here have used it as well.

Alex

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1983 300D (parked for four years)
2012 VW Sportwagen TDI Manual
2001 Miata SE
1962 Chevrolet Corvair Rampside