What Novak system for my e-revo running on 7 cell nimns?

[hpitraxx]

im in the same predicament as martin
ive got my brushed e-revo and i have a set of 4500mah nimhs
they do get hot and i would like to go for lipos but i dont know enough and i dont have enough cash.
i was wondering do you need one cut off for each battery or do u only need one altogether?
and which lipos fit in the e-revo battery compartments?
thanks