I like the digital WUR idea and would love to get my hands on one and do some testing. Maybe after I get my "new" headers fabbed...
Using an EBC to control the WUR is a nice idea, but unfortunately it won't work for most 930 applications. If you examine the dyno chart for a typical street build (IA fuel distributor, K27 or K27HF, & headers) you will find that 1 bar of boost is usually achieved in the 3500 RPM range. When examining the AFR chart for said engine, you will notice that enrichment is not needed until somewhere after the 4500 RPM range. An EBC will not be able to delay the enrichment late enough because the engine will already be seeing 1 bar at 3500 RPM. I can manipulate a stock WUR to delay enrichment until full boost is achieved without even using an EBC. Here's an example that shows "the best you can get" using the WUR alone. The blue curve is my car with my fully adjustable WUR and the red curve is David's car prior to adding adjustability to the WUR enrichment circuit. You can see that my car delays full enrichment until full boost is reached.
It's a big improvment, but still not good enough. The engine still runs way too rich in the mid-range, which is not only diluting the engine oil with fuel but also giving away horsepower and throttle response. By using an RPM switch, the boost signal to the WUR can be delayed until the exact RPM range that enrichment is needed. I think Brent 930 from the C2Turbo board pioneered this mod years ago on his car. It's a relatively easy mod to do and I have come up with a slick way to integrate it onto my car. Check out the pics.
I am using a factory solenoid valve normally used to control the smog pump to control boost signal to the WUR. I have connected it in normally open (NO) fashion, so that its failure mode will be to provide full enrichment. The mounting bosses for the AAV work perfectly as a place to mount the solenoid valve. It almost looks factory, don't you think?
Once I get the cracks in my headers repaired, I will put my car back on the dyno and post the results here. Stay tuned.