[gtr2112]

i just did it to mine with the same set up you're talking about. the power was great! stock motor, gears, and tires. awesome power. since i can't afford a fet mod for it, this is the next best thing. i'm putting 3 160mah cells in it tomorrow. more power, longer runtimes. to hook it up, just unsolder the neg wire from the car. then, solder the neg wire from the other batt to that spot. solder the 2 remaining wires together. that's it. the neg wire from the dual cell to the pos wire of the extra batt, and the neg wire from that cell to the contact. simple, yah? they should all be the same mah for best results, but it seems to work fine the way you were going to do it.