I was over on Helidirect.com and they sell a brand of Lipo called OutrageXP they are from Sweden and made by a company called Desirepower/Desire Battery
I'm thinking of getting 2-4 of the XP30 6S 2500mAh packs. They will be a perfect fit in my MBX5T in a 2P configuration. If you get any, please let me know how good they hold voltage?