Battery suggestions

[shady3031]

OK guys what i have is an HB LSP truggy i have a neu 1515 1y on the way. I already have a MM for an esc. I need suggestions for batteries--i currently have 2 4s 4000 packs that i picked up used. They seem to work fine but i am worried about running 30 min mains. I have been thinking os some maxamps packs prolly 5000-6000 mah but i am unsure of the voltage either 4s or 5s. I have 12-16 tooth pinions and the track i will be racing on will be medium to short with an occasional trip to a long track (200 ft straitaway). Would running a higher voltage pack make the system more efficient since it would not be running at its max all the time? Thanks guys and i am also thinking of getting artur to do a stage 1 mod to my esc.