The Tamiya shocks are just easier to rebuild and nicer looking.
I'd say if your goal is to go really fast, get a good brushless system and do some research on LiPo batteries, less weight and superior runtime.
The aluminum parts really don't help your car perform better. They weigh more but if you are having an issue with breaking a certain part, then aluminum *may* help (beware: aluminum parts can bend in cases where plastic parts would simply break)
Have fun smoking the nitros