Go to TQRRacing, they have a nice battery that fits the M05 perfectly, I use it and really like it:

http://www.tqrcracing.com/shop/produ....asp?p_id=2745

-also do a search on their site for "M05", you will find about 6-7 lipos that will fit the M05's nicely.

TQR- is my fav' online retailer for RC parts. It seems that all of their parts are really geared towards the RC'r who racers their cars competitively (as I do). They don't sell a lot of BS upgrades, most are purpose built to make our cars better. --just my opinion.