improve a littel bit the engine from the rs4 put it up to 450 hp, didnt cost as mutch as using a new or other engine in the rs5.
What i heard but cant confirme further rs models wouldnt have the bigger/wider wheel arches as known so far, due to aditional coast.
Would be really sad, and would approach them to the amg models, witch normaly have the same messurement as the normal merc models.
We will see