If your not planning on running stick or li-po batteries you may want to do this.
On the underside of the battery strap I've ground off the mouldings that sit between the batteries. With out these I found the strap sat/located on the batteries much better. That was before I even did the rest of the mod.
Have also reshaped the front of strap so that tubes are easier to get to when strap is in place.
On the battery posts there is a small moulding circle, that's were I drilled the hole for the pins to go in.
http://vmphoto.photobox.co.uk/album/5066758
Ran the car @ TRCC on Sat night & Q5 in the A

and finished 5th

but @ least the batteries stayed in place