This may be a topic for another thread, but here goes....what do you VX guys use for diagnostic devices? I've seen CDs for your laptop, cables, etc. But what actually works? I'd like to be able to monitor RPM while tweaking engine, get diagnostic codes, etc...

Not sure on that. I would just install a small tach under the hood.

For diagnostic codes, you need to "jump" the small connector above the ECU and your CEL will blink telling you the code. Do a search for a picture-explanation.