[coolhandcountry]

The more batteries the longer your run time. With the smaller kv motors you get less draw as well. You can go either way. The 2 4200 or 2 2100 basics. You going to get 2 speed controllers. I not sure on the 4200 but you should be able to go with the 7020 instead of the 9920. Will save you a few bucks. If you have two motors drawing less say 80 amp. You have two motors only drawing 40 amps. The amp draw is only guess work. You are going to draw 80 amps of power off 14.8 v. It is something to think about. I think the batts run in series is a better choice. JMO I may be wrong. I would like to see it get down. The other 2100 will take a 5s or 6s lipo. You can run a 3s lipo in series for a 6s. You will have some series get down. Sorry if confusing you.