493 HP and 516 lb/ft torque
VS
333 Hp and 268 lb/ft torque
Still there is a weight difference. I think SL55 is about 1000lb heavier. Am not sure, but will post exact specs when get home. Anyways, I have test drove the M3 SMG with the annoyign salesman, so I couldn't gun it. But I do drive the CL55AMG from time to time. Courtesy of my Boss

. They are identical cars, except the CL55 is a coupe. Yes, it is breath takingly fast. In pure form on tracks the M3 will win, but on the streets and straights, M3 has no prayer for, against SL55.
PS: I also get to drive S600 from time to time. Which is, V12 6.0 Liter TWIN TURBO. 493HP - 593 lb/ft Torque.
It is quite disturbing to drive a 4 doors luxurius sedan which can humilate exotics such as Porsche's, Ferrari's, Vette's, and even few purpose built race cars.