I use a TrakPower Lipo and it fits, just. I did have to Dremel a notch so the lead could plug in to the battery, also I needed to solder one lead to a 90 degree angle to clear the prop shaft.
The only upgrades on mine are 3Racing graphite shock towers front and rear, front graphite brace, rear aluminum brace for the gear box and one for the suspension.
I tried the 3Racing steering knuckles but they bent literally on the first tumble, 30 seconds into use.
Novak Havoc 3s/Ballistic 8.5T stuffed in there
Picked up this Tamiya smoke parts tree, gives you the spur cover, body posts, front skid and wing mounts