At Jeff B, I've looked into it and it's literally impossible with the RS models because they're categorized as completely different car models. Since the C6 RS6 for example was never exported to the US, it cannot be registered and would be difficult to import. The only way to do so would be as a show car or show piece. A Canadian company tried to import them and sell them in the US and they failed miserably unfortunately.
You could import a Q7 V12 TDI most likely because it's just a different trim and could squeak by, but models that were never imported are a different story.
@Viking: the Scirocco R in the UK is 1400 pounds less than the Golf R.
High power FWD cars are becoming a bit more popular. A bunch of manufacturers have or are going to have a fwd performance car in the US. Focus ST, Regal GS (kinda), Mazdaspeed3, etc.
Speaking of the RS cars... Where's my RS3 Audi?! :(