I also have the GM SX6 Purple High performance speed control 10 turn limitl. And it is one hell of a good speedo if you dont fancy going below a 10 turn. A good point is that they just don't heat up, at all. I mean you could be eratic and rag the tits out of the car and it may only just get a little warm at most. A really good buy if you ask me, i used to run it in my b4 but now i use it in my 12th scale, as it is that small and light.
The wires that come with the speedo probably weigh more than the esc itself.
