The only part you NEED to fit them is the intake pipes, as the intake on the turbo is larger.
500 is properly wringing the neck of the RS4 K04's
But various other parts are required to get 500hp irrespective of turbo. You'll need 3" downpipes, full exhaust, sports or no cats, big frontmount, injectors, fuel pump.
The heads and inlet manifold etc start to become restrictive around there too, so if you want much more those need upgraded appropriately.
Anyways this is all a bit distracting from the original post, so i'm going to split it all out into its own thread.