The very first thing you should replace is that plastic lower hull with the crappy suspension and get one of these

TIGER 1 METAL LOWER CHASSIS & SUSPENSION ARMS

With all due respect to Marc, I'd stay away from the Mato Tiger, since it's really just a metal copy of the Heng Long hull with all it's flaws and that same crappy suspension. Proper torsion bar suspension is the way to go if you're adding all those metal bits.