[JLMounce]

I didn't have to myself. I run my tach wire off a chinese HEI and haven't had issues. No shielding either. I also run my wife's Go Street tach signal off the Accel HEI in her Chevelle. No issues there either.

HEI's are also kind of notorious for having a dirty signal, but in my case I haven't run into any issues. I just try and route the blue tach wire as far away from the distributor and spark plugs as possible.

I think generally, if you're running shielded plug wires and resistor plugs, you're probably okay. Anecdotally, the people I see with rpm noise issues run cheap wires and non-resister plugs.