According to this RS buyers guide there is a phase 1 and 2 focus RS mk1.

http://www.strikeengine.com/ford_foc...ing_guide.html

They write:

However there are two phases of Focus RS the "Phase 2" cars had additional stitching at the base of the front seats to prevent them sagging (this can be added retrospectively by a Ford Dealer) a pink grommet on the throttle cable (which reduces vibration), engine start written around the starter button and the removal of the dimmer on the clock.

More importantly the Phase 2 cars came with an updated dated engine map. The first map being called AE, the more recent, AF. The new map improved fuel economy, drivability and starting. Ford dealers are able to upgrade the early cars to the more recent map but we don't know of the costs involved. When buying a Ford Focus RS be sure that you ask the seller if this map upgrade has been carried out.

Ford states that the "minimum" power output of the 2 litre power unit to be at least 212bhp with some owners finding outputs to be as much as 230bhp.