there are a bunch of these on ebay for 80 bucks, I was wondering if anyone had any dirt on them? How well do they work? Intallation? How about going down hills?

We put one in my friend's F-150. Installation was pretty simple, the kit comes with a variety of brackets that you use to mount this little stepper motor that connects to your throttle arm, then it has a control panel that goes inside the car. It does not compensate for your actual speed, it just holds the throttle open at whatever position it was in when you press "set" on the control panel. So you will lose speed going up hills and gain it going down hills. It does have resume, accel and decel features.