I'd never thought about it that way, but you make a good point. Still if they import a limited run of the Focus RS, they would be a lot more exclusive than a regular mustang that can be had with several engine/tranny configs (and thus allowing the RS to be sold at a higher price). I also think they could be sold to slightly different audiences, which I'm guessing could also be the case of the 335i vs M3. The 335 can be pointed a bit more towards the luxury end of the scale (or at least that's the impression I have) while the M3 is more focused; that said I do find it crazy that they can get 90 HP more out of the engine with just a chip. I'd like to know if those engines won't blow up after a while, or become a lot more twitchy.
Regarding the Focus RS they're "testing public reactions",
Here's one in the streets of Mich.