Just bought an exhaust servo for a CBR600. It runs cables that close a baffle in the exhaust for more backpressure. Should have enough power for the throttles, which I will set up to open only part way. In addition, it is already set up to run bowden cables. I will reverse engineer the input, and set up a micro-controller to run it.
I will also run a PID (Proportion, Integral, Derivative) control, which will provide smooth, adaptive control for the speed.
Total cost, so far:
$8.50 for the Servo
$ 19.90 for the micro-controller, and related stuff for easy development (arduino clone). Final cost for additional units will be 5 bucks or so.