I know the noise you're talking about.
My mom had a '94 C220 that was noisey at idle, kinda like a fork in a garbage disposal.
There is a young kid who lives in my townhouse complex who has a C230 Kompressor (he's Chinese with parents that spoil him), and when he drives past my unit in the driveway, you can hear the difference between what a normal C220 / C230 makes and what the Kompressor's make.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".