Brave - I didn't say anything specific about an ECIS exhaust. To the best of my knowledge, ECIS don't make an exhaust, they off the (highly acclaimed on bimmer.org!) Active Autowerks part (as you noted). I believe my comments to be true on any after market piece. On the CLK55 note, a new M3 would out class it. The new C32 AMG does do 0-60 0.2 quicker (4.6 vs 4.8) but the M is still considered the better sport sedan. I think a CLK55 is somewhere in the mid 5s to sixty.