Im writing this today to advise fellow owners, of the applicable make and model, of an issue related to the emission system that I feel needs to be corrected. I have encountered countless stories of other owners who have had lag or hesitation after a cold start and while at cruising speed. Some may also have a very high pitched squeal during start up due to this faulty part. (Secondary Air Injection Pump) This pump is what pushes the necessary air flow into your exhaust to burn off any pollutants and harmful chemicals in the catalytic converter. This is a very big problem for many and as I have found, when attempting to diagnose this issue VW mechanics defer from this and advise you of an unrelated problem. It is my sole opinion they are aware of this issue, however, do not want to acknowledge it due to a costly recall. If unchecked this defective part can cause incorrect air flow into the exhaust and can even result in a stall during hesitation causing an accident. Many others who have taken the time to research this issue and have had VW mechanics replace this part have stated that it fails again shortly after. The pump is held together with rivets that are unable to withstand the air pressure causing air to leak. This part is very expensive and the correct revised part is held together with screws and bolts. I advise anyone having an issue related to this problem to take your vehicle to a mechanic and have them test your emissions system. If this is your problem please also contact the EPA and NHTSA to notify them of this personal and environmental hazard. Vw chooses not to replace this defective part with the revised part to correct this issue and should be ashamed. I am assuming unfixed issues such as this are a direct result of the many negative complaints on this website. I was going to give this car to my mother and purchase a Vw Tiagan until I was denied a free of charge fix for this issue. Just this one faulty part will cause havoc on your vehicles performance and will ultimately negatively affect other engine components and sensors. Vw has achknowledged the MAF (mass airflow sensor) as being faulty, and it begs the question as to if they are just fixing a part connected to the problem, instead of fixing the main problem, to appease owners and save themselves a costly recall. Short explanation : Secondary air pump regulates to the combi valve and to both solenoid valves, then to cat converter. The incorrect air flow resulting from this issue causes hesitation, lag, acceleration surge, stall, sputtering, squealing, and can also allow harmful gases to leak into the atmosphere. THIS NEEDS ATTENTION VW!!! I just had to replace my cat converter a month ago and wish I had done my research beforehand. This is all solely my opinion and I advise you to download a copy of a Bentley Vw Auto Repair Manual to calculate your own conclusion.