I have cut off the front grill as when hitting stuff (especially sign posts!) the bumper flexes so much that it shattered the frond end of the shell
Cut out the triangles just behind the roof to aid cooling
Replaced the steering servo horn for a stronger one and mounted the ballend on the inside of the horn to eliminate some of the flex from the mechanism (could do with a faster servo)
Removed the rear brace and made a new rod which mounts onto the center diff mount and then made a 'top deck' which mounts on top of the center diff rod end to the front gearbox.
Cut two plates measuring about 110 x 50 covered them with 2mm foam and put them on the body posts and the body on top. This stops the shell from flexing and bouncing all over the place and ruining the looks when in action
Filled the center diff with grease
Stripped down the axles and applied bearing retainer to the bearings (still some to do) This helps remove vibration thus increases top speed
Also used the same bearing retainer on the suspension arm pivot screws to eliminate the play in the joints. Works really well, I cover the whole pin and put a bit in each hole. Once reassembled I work the arm back and fourth every now and then for 20 mins.
Used an aerosol lid to make a cover for the air filter. Tried with different lids as many are brittle. Drilled 6 6mm holes in the top of the lid at 11, 12, and 1 o'Clock and at 5, 6, and 7 o'Clock positions. Then drill a 12mm hole in the middle put the air filter inside it and through the middle hole, then push the rubber pipe on which holds it in place. To stop the air filter falling off when in use I made a wire brace to support it.
If any of this interests you I maybe convinced to take a few pictures and write better instructions