If you mean the mod that allows you to...

1. use the airsoft cannon synchronized with the shell / reload sound...
2. Control the elevation motor to run in BOTH directions instead of cycling through in one direction. (on a mode 2 transmitter - it's LEFT stick at 75% up from the bottom and then use left and right movement to control elevation up and down)

Then follow my guide here...

http://www.rcuniverse.com/forum/rc-t...l#post11671841

Need to reconnect (or resolder) 1 wire. Basically its a splice.

Then you need to SWAP the position of 2 other wires with each other on one of the plugs. See photo on the guide on which wires and what it should like look.