i've searched about this. At highway speeds, i'll shift from 4th to 6th and i'll let the rpms tomce down to what the drivetrain will be running, but it takes a good 10 seconds sometimes for it to go from say 3500rpms down to 1500ish. i'm not realyl sure where to start. could me tb be stuck open a little bit? i searched rpm hang, but only came up with low speed stuff, which my car does too. Does my car need a tune? its stock besides a lid and a catback. its a 01 m6.