Hi I can strongly recommend one of these, tried many speedos over the years and this one is lovely to drive with, currently running it with one of their matching 7.5 motors and it has lovely response and awesome top speed.
Just make sure you do get the program box, although the standard setting is pretty good there is so much more to get out of it.
http://www.hobbyking.com/hobbyking/s..._10th_ESC.html