did you happen to buy a car that had a lipo tray? or does it have the tray with the round releifs in it? ie a lipo wont sit flat?
Wolfhobbies made a lipo tray for this car. not sure if its still out there. there is also the e4d which supports lipos out of the box, but its chassis doesn't have a cutout for the lipo, it drops in from the top.
your best bet is to try to find a wolfhobbies lipo tray, or buy another e4 that has this upgrade already.
which.. if you were so interested, i happen to have available