Thank you Scott that is some good work. That is also how I understand the Dukes valve works. I will try to get this done on my L4 this next month while doing the annual. It is by far the simplest fix I have heard of. I suppose that if there isn't enough vacuum volume then just putting a small storage tank or larger size vacuum line should do it but I think that if the valve is off it's parked seat when you give power up past about 25 inches that we shouldn't get a momentary pressurization over boost. Worth a try.

Jim Hergert
N6XE, "An Sex Y" L4P