Lots of variation in both price and quality. The MB part is a known quantity. My son has had to replace his cat 2x. It was bought with an aftermarket cat that was an early replacement for another aftermarket cat which failed. The replacement recently started to rattle like a snare drum on acceleration and needed replacing. The muffler shop told him $350 for a replacement, saying 'the cheaper the price, the shorter the life' on aftermarket cats. His lasted him about 18 months -2 years from the time he bought the car!

On the other hand, his GF has a Mercury Cougar V6: Both of her pre-cats are showing a fail code and need replacing in order to license the car (moving here from Ohio). The pre cats are built into the exhaust manifold and are not available seperately. Buy from Ford and install at dealership only, according to 2 muffler shops and 2 Indy garages. $2200 parts and labor, which includes a cheapie aftermarket main cat at $150 as part of the pkg!

Pre-cats on MBs can go bad as well, but on my 87 theyy at least are not part of the exhaust manifold. I would consider a good aftermarket cat that is well recommended by someone you trust - just be prepared to replace it more frequently, maybe much more frequently, than a factory cat. I don't know about the precats as aftermarket units, however - I haven't seen them offered.

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John

2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)

Click to see 87 300E