A few more details I've been able to glean from other sites about what a Brabus 3.8 conversion gets you...

Custom crankshaft with a longer stroke, finely balanced rods, larger pistons and an enlarged bore... custom camshafts, BRABUS high-performance metal catalysts and revised electronic engine management system.

Also, an SLK with this package (and Brabus exhaust) was reported to do 0-60 in the 4's (4.7 to be exact) and the quarter in 13.2 sec @ 106 mph.

Yikes!! 8-o