I just replaced mine on 87, 260E (>350K miles), and let me tell you, the car instantly transforms into a car that is close to being as good as it was when it was new.

I bought a Catco converter from one of the online vendors, for about $250, it does not have the pre-cats, i.e. those black bumps before the actual converter. I had it installed by Midas, and they charged me close to $250 for installation. However, it can be installed by smaller shops (Mayco etc) for less than $100. I also got my exhaust manifold seals replaced and that cost me $250 more, but again smaller shops would do that for less than $100 too.

I cant say how long it will last but it certainly wont last as long as the original MB ones. I think the performance and the life of the CATs are directly proportional to the cost one pays. But if I get 5 good years, I would be happy and next time I will not go to Midas.

If your CAT was clogged because of burning oil, get the valve stem seals replaced also, this can be done by some good mechanics without dismantling the engine.

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Saumil S. Patel