If 'growl' is good and screech is too far......... Is there a telemetry output we can use to actuate bass shakers when there is traction loss based on that? Scawan must be using some formula to generate the tire noise output and I do not care if it is real world accurate etc. or if it is proprietary. Would just like to actuate my bass shakers using the same signal my ears are queing off of. Would be really nice we could access that signal for all 4 tyres.

You do have access to that signal at the output of your sound card As far as I know, there is no other output of such events via inSim (telemetry) yet.

What most bass shakers do is take game audio signal and extract the certain frequency range that corresponds to tire scraping noise. This is usually done with a bandpass filter, by use of FFT (fast fourier transform). After that the app usually connects to a serial port of arduino and sends some numbers to it, then arduino outputs a PWM signal. You feed this signal to H-bridge amplifier and then into your bass shaker. As simple as that. I think I've seen somewhere already such projects, it should be relatively easy to find.