To change the reverse speed on the MMP, you would first have to get the Castle field link card, or some other devise to connect the card to your computer. On the computer that you are using, you must download the software from the castle site. Once you have the software downloaded and a device to connect the ESC to your computer connect the ESC to your computer open the Castle Link software. One of the adjustable parameters is reverse speed.
Associated SC10 4x4 (CC 3800kv- CC MMP ESC)
Associated RC10 T3 (CC 5700kv- CC Sidewinder ESC)
XTM X-Cellerator (.18 XTM nitro)
Tekno SCT 410.3 (CC 2400kv- CC MMP ESC)