I've been trying LiPo in my baja and I'm convinced LiPo is a Bad way to go. I think my frustration is because of the LiPo regulator, not the battery.
I've been trying because I shortened my chassis and needed something smaller would still feed enough power to keep my servos.
Go with LiFEpo4. Kent at Killer RC
can hook you up. This is by far the most fantastic way to go to power your baja electrical. I don't need a regulator and they are much safer.
The 6.6v 3200mAh LiFePO4 receiver battery pack is $49.