roadracer,
regarding the max boost you can apply to the engine, people will tell you different numbers and give all sorts of different reasoning. I'm not sure what the safe proper number is but I have mine maxed out at just below 14psi. It seems to work well and it sounds like it's within the realm of normality. Oh, and besides, if you over boost it too much, there is a safety valve that will release all the pressure to keep the engine from blowing up.

Alex

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