Disclaimer (Ha!): While this may be my first post on the MSP board, I am not that new to MSP's and I'm certainly not new to turbocharged cars.
It is true that waste gate actuators do not like negative pressure. It is true that a one way valve is the functional part to alleviate this. In fact, some manufacturers put them inline with the WGA signal line. Also, look at any ball and spring type manual boost controller. They accomplish this function in exactly the same way; its sort of a side affect to their initial purpose.
Some of you are worried about over working a turbo charger because 'the WG would be stuck open since its actuator never experienced vacuum after boost'. This is not the case. The very nature of a one way valve is to have a pretty weak little spring. As you come out of boost by reducing throttle slowly, abruptly, whatever, that check valve isn't going to be allowed to seal off vacuum pressure until almost all positive pressure is gone. There is plenty of time and ability for the WGA to pull shut. And then, oooo nice, its not being pulled into oblivion every time you're in vacuum.
As far as the one dude up there saying something about a short block being available for anyone who needs it, well that's just a little overstated. As long as you install the check valve in the right direction and monitor its condition periodically for leaks, no harm will befall your engine from this simple modification. In fact, you will be doing you WGA a favor. Another thing to do, for perhaps more peace of mind, would be to get an automotive grade check valve as it would be more suitable for the heat. But I like this little guy form Lee's.
