Li-Po or NiMH? I'm confused.

[RC-Monster Mike]

The 3s Lipos will reduce your top end quite a bit compared to the 14 cells you are using now. Your punch will probably be pretty close, depending on the cells you use. I would pick up a couple 3s packs and a couple 2s packs and run them in pairs (a 3s and a 2s in series to give you 5s). This would be like a little over 15 cells worth of voltage (nicad/nimh), so you could drop a tooth or so and retain your speed, but pick up some runtime from the lower weight and increased capacity.