There is also the AAI kit that swaps out the manifold and adds the SC to the top of the new mani but that is a very rare piece to find. The M62 SC is "easier" to find but is very much not a "bolt on" kit and a turbo kit on our cars is much easier.
Robhill there are a handful of build threads on here with SC info and a few are currently running with a SC. There are reasons people prefer "bolt on" kits for our cars besides the money involved.