I was always under the impression that this change to the exhaust would only result in sound and or maybe a bit of lost power because the c32 (m112k) guys have done this w/ little to no positive results. Then recently a c55 owner (m113) removed his secondary cats and got some good power:

http://mbworld.org/forums/showthread.php?t=263590

I figure, the m112 folks would benefit in the same fashion (w/ 25% less gain though) because we have no requirements for forced induction like those of the m113k and m112k. I dunno. Seems like a pretty affordable lil change that could get us NA guys some more oomph.