[itsnota2ma]

Okay, I am looking for your opinion. So, I just had my engine replaced on my 2012 550i w/140k miles and injectors replaced, because I had a faulty one. Now I have a clogged cat and my indie wants to charge me another $6400 to change the cats after I just spent $20,000 fixing the engine. So here are my choices:

1. Buy new OEM cats and install them myself - still like $4500.
2. Buy used OEM cats and install them myself - about $1500?
3. Buy new high flow cats and install them myself - don't know how much.
4. Buy new down pipes and install them myself - about $1500?
5. Get out while I can and take a loss.

[Jalumi69]

https://f10.5post.com/forums/showthread.php?t=2044554

There is a PDF from BMW in that thread posted by @Hoa, on how to clean them - Worth a try as they are so expensive.

[mcdanielvzw]

I originally went for OEM 2.75" downpipes and the delete kit from ARM.
2 real issues:
-Install wasn't the worst thing I've done, but the heat shield doesn't fit 100% the way it did stock
-The delete kit moved the O2 sensors to a place that interfered with the stock airboxes..... Soooooo I ended up needing to also get a CAI that would remove the stock airboxes

No regrets here, and I don't have a light on 98% of the time (back-end O2 code still registers I believe) - I had an unrelated issue with low hydraulic fluid and the DSC system, but that was remedied. The car pulls noticeably harder and sounds great without being what I consider obnoxious.

Total cost would be about $1100 for the DP, Delete kit, and front facing intake kit. Labor not included of course, I'd recommend 2 people and a lift of some sort.

I'd presume, even to sell the car to recoup your money you'd need to do something with the Cats so it runs right.

[itsnota2ma]

UPDATE: So after some searching, I decided to go with the high-flow Cats from Racing Dynamics. The price point was right, and I did not feel like farting around with the CEL for the O2 sensor. I am still in the process of installation. I was really concerned my independent mechanic mis-diagnosed the issue, because I could not see anything wrong, but once I got the one on bank 1 out, it was quite obvious. It sounded like it was filled with gravel.

So the Cats from Racing Dynamics come with a heat shield welded on. Do you think it is necessary to re-install the rear heat shields?? I will however, put the firewall heatshields back on.

Also note, cleaning was not an option here.

[ChiltiCoatl89]

Congrats on the New cats! are you going to tune it?