Thanks for the rev limiter tip, it just made my car drive great!

Have you tried getting your tach signal from the ecu tach output, and not the coil? Do you still get spikes?

Are you sharing the the crank signal with both the stock ECU and the MS? This will cause noise to be soaked in from the non-shielded stock crank signal wire.

Each of these questions are important to me, as I'm trying to figure this thing out for us. I cutting the crank signal to the stock ECU would put it into complete standalone mode. You would have to have the MS relay switch on the ASD relay to power the injectors and coil, because it won't if it doesn't see a crank sensor, you would have to try powering the crank sensor with 12v, you wouldn't have IAC control because it wouldn't think the car is running. None of this is really a problem though. I just hope if I do all this the noise will disappear.

Joel Baldridge, ASE Certified Master Technician, Audi Certified Expert Technician