LRP Vector X12 Brushless Modified - 3.5t 10,000KV @ 76000RPM as a start, but there are others out there capable of even more frightening speeds.

If you are really serious about getting into speed, the best place to start would be with your local RC Drags Association or RC Speed clubs, then work out a budget and start from there.

I have an RC Funny Car with a 5T motor running 6S and its insanely fast, i could ramp it up a lot more using boost and timing, and take it out to 10S, but super speed is not my thing, consistency is and heat is not an issue when a race is over in 2 seconds so you can do insane things.