for the rs4 -3 , hop ups are more or less what you want. some like the carbon fiber upper deck, some dont. i have the carbon fiber deck, and the rechargeable receiver battery (instead of AA). thats pretty much all i have done at the moment i think. but if you switch anything to aluminum, just remember its going to add weight and is going to bend, unlike the stock plastic that will give. carbon fiber i personally think is the way to go, but on some parts you just are stuck with aluminum.