Quote:
Originally Posted by Dave07997S
This is incorrect. If you remove the cats farthest away from the headers you will not get a CEL for cat inefficiency. As the cats that the rear 02 sensors monitor will still be in place.
Dave
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Unsure I understand what your saying...both primary and secondary cats have 02 sensors....correct? If you mess with either one at different times or together who cares.....codes and the MS660 will know so BMW will know..period. You can try to fake the system but believe me they can see everything the computer throws up...and 1+1 = modifications = possible warranty refusal. If you got plenty of money and don't care about this, then forget what I am saying. I have dealt with this issue with a friend and Chevrolet and exhaust modifications that they tried to say was part of multiple modifications that actually did not exist. Chevrolet tried to imply that this was part of the cause for engine damage...Now thier claim did not stick as they could not prove other modifications but they tried, and it was a PITA. If you want to deal with maybes and hope that BMW will continue graciously hand out good will to modified systems as the years go by then that is your call....everyone has different varying degrees of risk they are willing to take and money...good luck!