The maximum lipo height that will fit in the CAT SX is 24mm, this would exclude batteries like the new Nosram/LRP 50c and the new GM 50C.
For those of you that
think
you need more power from the 2010 spec list you could use;
GM99003 - GM Racing 5400mah 45C
SLR55485H - Speed Power/Passion - 5300mah 45c
NR99971 - Nosram 5300mah 40c
All these will fit fine.
The Cougar SV has no height restrictions for what's currently available.