Which lipo to go with?

With my 10.5 (around 4200KV) bashing, im getting a solid 25-30 mins, I can get 50 mins if im not so aggressive with the gas, and pulling wheelie's, all of that stuff......

Ah poop, I was at my track today and found out that you can only use hard-cased lipos for racing and must have a liposack too. This means that I have only 2 options, right? Trakpower and Neu car lipo? Should I consider any other lipos? What about li-ion? I was thinking of a 2s1p a123 pack, but don't know if the voltage will be enough. I use about 120mAh a minute, so about 1000mAh for a 5min race; I think 2300mAh(a123) would cut it. Opinions/Suggestions?

Thanks!