E-maxx bushless set-up ? Newbe

If you aren't worried about too much speed, a friend of mine is running a stock emaxx with a mamba max 4600 system on twin 3S 5Ah packs run in parallel. Like I said, it's all stock so it's pretty light. Although I told him that I didn't think it would work, he hasn't had any issues with it. It runs cool, has good power and runs for a LONG time. Most times, he doesn't even bring the charger out when he runs it. By the time the batts dump, he's ready to leave anyway.