Lazer zx-5, what should I upgrade/replace next?

[littlened]

I bought the lazer as an RTR last june, and it's only been raced once (I've never had time to go). In the meantime I've been changing bits and bobs every now and again.

So far;

Proline Body Shell
7.5t Brushless Motor, Orion Votex Speed Controller
Acoms 2.4Ghz Kit with new Server
New rear wheels, I read the RTR wheels were made from poor plastic

I've also made some changes to make it more like the SP.
SP front wheels
Front and rear diff shafts to replace the plastic ones
Replaced the bearings in both gearboxes.
SP front and rear driveshafts
SP Front/Rear wishbones & hubs etc
Aluminium suspension holders on the front (I broke the plastic ones in my only race so far)
Set of front and rear shocks

So I'm wondering what I can do next, or is it about as good as I can get it? I know I've probably spent a fair amount on it so far, but just upgrading it has been a hobby in itself, which has taught me alot about the car.

Some possible upgrades I'm thinking of are to get a set of hex screws, and I'm possibly thinking of getting the carbon fibre top desk and chassic, but I've read that the standard chassis is actually better (more flexible?). I could probably do with some aluminium suspension holder things on the rear as well, as I don't expect the plastic ones to last long. Is there anything else?

Here's some pictures of it so far...