I've recently upgraded to the Schelle stretch carbon chassis, it really makes the car more stable and it jumps much flatter and is more stabile. Highly recommended.
I'd definitely suggest an alternate for the ball cup/ball stud combo as this is where the majority of the car's slop comes from. Also the exotek bushing set and steering rack is near must have to eliminate the slop. I'm not one to try and make everything super tight, a little bit of slop is a good thing! A really tight car won't perform and will be hard to drive.