Vu has got it right. Most places that POS 200 dollar cat will cost 2-3 times that. The real thing lists for over $1700 just for the part.
Burning more than a quart every 1000mi is filling the intake, combustion chamber, ring lands, and exhaust with carbon. The seals require 3.4 hours by the MB time guide and list for $14.50. Use only genuine MB seals.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician