Do you have any experience with the Turnigy Heavy Duty batteries? I have been looking into getting some of them but am not really sure if they are decent or not.Turnigy Basher 6S 4000mah hard case
Can't beat this pack for the price, they're around $50. These packs have worked great for me. They don't have the best IR but that is to be expected because they're so cheap.
Turnigy Graphene 6S 5000mah soft case
This battery is a beast, they can handle big motors and big pinions with ease. They have a super low IR after tons of abuse.
SMC 4S 6700mah hard case
I only use these when I need to go slow (rc track). One of them works fine but the other pack is starting to lose a cell.