ORIGINAL: BigBrett
hhere ya go is a guy running anew emaxx on twin 7cells.This can give you real good idea . i did a lil more research on the lipo's and most peopl are saying dont do it for you fry the stock 550 motors . If you decide to go brushless then run the lipo.
look into the 7cell Ib batteries unless you have the older version then go 6ell
http://www.youtube.com/watch?v=gl5QLlvdY1Q
The 7 cell sare mor elikely to burn up the motors than the lipo, due to the higher voltage.