I wouldn't do that. the AFM leads are what, 18ga? 7-way trailer cable is 6-12/1-10 (that is 6-12ga and 1-10ga) overkill. solder in new wire of the same size as OEM, and heat shrink the connections.
Cool, I'll do that.
Bigmike, thanks for the tip and sorry, I erased your post by accident. The old positive lead was around 3ft, the new will be 6ft. This only goes from the + to the starter so I don't know how hot it will get but I would definitely like to get energy to the starter with as little loss as possible.