I noted that there has been discussions concerning the MAF/AMF but without any conclusion specifically concerning the aftermarket filter systems i.e. GruppeM, K&N, Simota, BMC, etc that contributes or not the faults in the MAF/AMF.FYI, I for one has experience it. My autogearbox changed became jerky during down and upshifting between gears 2 to 3 BUT at higher speed it was alright. This came together with the gearbox indicator lights. Was adviced to turn the ignitiion off and start back again. It worked. Next came the GTI dianostic test. Yup...it came out the MAF...that was erased. So far the indicator has not, for the past few days, come on and no more jerking/unsmooothness of the gear changes. My mechanic may have suspected that this is largely to the MAF/AMF acting strange due to my carbon fibre SIMOTA air intake system. Now after reading past years discussion on this, it came to my understanding that there has been no conclusive evidence that holds water that aftermarket air filter system contributes to this failure. Any comments or advice as to (i) the MAF/AMF faulty myth (ii) my jerkiness is as a result of the MAF/AMF.Cheers