Just for the record, my former car, a 1993 300E (3.2), always had problems passing smog.

I replaced the cat with an aftermarket unit, and it would always pass, but just barely.

After two years, it would fail again, and I'd repeat the process.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".