Top speed I've done in the M coupe was 153mph (GPS-recorded) somewhere in "Mexico"
This was done after I had my ECU tuned, which supposedly removed the factory speed limiter; but I've yet to try it out to see if I actually got what I paid for
At the time, my speedometer read somewhere between 160-170mph. I didn't really take my eyes off the road in front of me for obvious reasons.
Not sure if ECU limits at speedo indicated 155mph or actual (e.g. GPS-recorded) speed