Thanks for the link and advice. I have had a look and it seems some people use these :

https://hobbyking.com/en_us/hobbywin...B&gclsrc=aw.ds

Although the esc can run 2 motors I am assuming I will still need one per motor as I will need each motor to turn a different way from each other when I want the bot to turn. I have read that I will need to do some sort of channel mixing on the DX7.