Originally Posted by Kolyan2k
its actually seems to me that you have no idea what you are talking. Many people remove cat converters for performance benefits (called "test pipe" mod), and I have done so on 2 of my cars. Both passed inspection just fine. I believe only CA has different emission regulations which MIGHT prevent you from doing test pipe on some cars
The way cat converter works is when its cold it simply passes much more toxic crap, and it only works efficiently when its running hot. Sooner its warmed up, better it is for environment, and better it is for BMW because now 335i runs greener.
If you remove the cat and get a tune or some other mechanism (spacer, simulator) to disable or implement false o2 readiness/readings, then you could pass, depending on the test used. Many jurisdictions have a combination of a visual check, o2 readiness check and a tailpipe sniffer when performing the tests.
Your statement that you will still pass if you remove the cat is unfortunately very wrong. You might pass with other modifications and only if they are not doing a visual check and tailpipe sniffer.
Also, cut out the attitude - your description of how a cat works is worse than what a 9th grade chemistry student could describe.