Earlier this morning I rode my '16 GTL over to BMW/Greensboro and distance of a mere 20 miles one way all Interstate to arrange for a service appointment on February 28, 2020. Never ever had a performance complaint whatsoever on my previous 2014 GTL nor my current 2016 GTL but dog gone it; she 'walks th' dog' now boys! Don't ask, 'cause I don't know exactly what the Stage II files do, but I b happy. In talking with Chris at Bren a few weeks ago all I could ascertain was the Stage 1 is the go to upload when using 91 RON premium unleaded gas and Stage 2 is the go to upload when using 93 RON premium unleaded gas. In my area 93 octane is readily available at just about all gas stations-thus my choice for selecting the Stage 2 uploaded files. For those of you that have the 2018's and above your results may differ.