My car gives me 9 psi. The low end and midrange is much nicer. It is starting to run pretty well. I want to get a bit more out of for those times I might be passing on a two lane road.
I have seen the manual boost controllers they are very inexpensive Mine is even less expensive. What fun is it to buy one when you can make it.
Here

I am going to test the pressure that it builds and either increase or decrease the spring tension. I also need to drill a small bleed hole on the waste gate side of the valve to relieve the pressure once the foot feed is let off.
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I am using a chrome plated round head screw as a valve. With the brass body as the seat. It is what I had handy
I will be sure to follow up.