You're looking at +/- 203mph depending on tire size.Yea, the TCU only sends the RPM request for launch control and downshifts. So I don't think there's anything I could do on dme side. Its too bad it doesn't seem to gets rpm signal from dme either. You could yellow box all the wheel speed signals going to the TCU but that might have some negative side effects.
Isn't M3 redline 8300? What would the max mph be at 8k with a taller tire vs. 8300?