Ian,
I'm curious as to why the RPM gauge is segmented in decreasing decimals? Is this a European standard? Is there a way to turn that feature off? The standard US display of every a tick mark at .5 would be very nice. It confuses us across-the-pond'ers, at least me anyway.
1.9
2.8
3.7
4.6
5.5
6.4
7.3
8.2
9

A really cool feature would be to have the numbers light up in a different color as the needle hits and passes that number. It would have to work in conjunction with the user defined pointer/tick mark color setting though :). Or, make the number slightly larger/bold/etc. to place more emphasis on where you are on the dial. A circular bar gauge around the dial would be cool as well.

An RPM set point would be cool. Like an over-rev setting at 7k and all numbers after 7k could be set to a different color and/or once you hit that set point, the gauge would change color.

Why is it dangerous to add PIDs that you are unsure that will work? How does adding an unsupported PID damage the cars brain? I was under the impression that scanners just read codes. Is this because of the CAN technology where sending the wrong code through the wire can issue a command to the brain to do something undesirable?

I think you need to hire more programmers 🙂 Great app. Thank you for writing such a great and functional tool.