7-cell vs. 2s lipoly

[pedeboi364]

Lol, pls don't hunt me down for running nimh. I wana upgrade my power for my B-day, and my dad told me to consider what i could get with the money i would spend on lipo. So far, i run:

Stampede with:
novak SS ESC
LRP 8.5t X11 motor
6-cell 4200mah pack made of IB cells by proboat


I was thinking of going with a protek lipo ($40 for a 4000mah 2s on amain)
and a Turnigy accucel-6 with 14v 16a power supply
That lipo setup would cost about $175 (I'll also be getting some misc. supplies like heat shrink, wires, connectors, etc.)

I currently have a Dynamite Vision Peak 2 charger that does my current pack pretty good. It only false-peaks occasionally.

Now my really questions: What kind of performance will i see over nimh with that aformentioned lipo or other similar lipo? What are some good 7-cell packs for the stampede?

Thanks in advance!!