I have headers and aftermsrket cats and pass emission every year. No cat efficiency errors.
For ms43 and higher, the post cats do affect fuel trim. Ms42 is only for emission. Ms43 makes minor adjustments to fuel trim for post cats (keyword minor)
sent from my HTC EVO+ using Bimmer App
Last edited by flashmeow; 01-18-2013 at 11:35 AM.