Someone posted a while back at how constricted the E60's exhaust system was.

I would not put it past BMW to bump up the HP from 507 to around 550+. Especially considering you've got the RS6 coming out soon as-well as the recently released E63 AMG.

Hmm, The rumor I keep hearing/reading about is that the M6 CSL was going to get the tweaked engine. Maybe a change of plan since the competitors have come on so strong?

Makes more sense (to me at least). The M6 has such a limited market, creating CSL's would be crazy - would there even be such a market for such a car? People looking for more performance over comfort in that bracket are probably shopping Porsche's at that price range...