To be completely honest with you Steve, I would not buy the carbon chassis or aluminum one. With aluminum, the chassis bends and when it does, it is completely useless and a waste of money. The plastic is just as strong in my opinion, as it has internal ribbing and bracing running along it, whereas the metal is only flat and rely's only on its metal properties to provide strength. The aluminum is way more expensive and the carbon fibre even more. For me, I would just stick with plastic. However, the aluminum parts that I would get would be the rear trailing arms, rear driveshaft, rear trailing arms holders, maybe rear links and any other bracket thing that maybe a weak point. Also if you plan on installing a way stronger servo, the steering links and front wheel holders maybe worth considering to get in aluminum. This is just about all I would get in aluminum, the rest would just be a waste of money.