Starting in 2000 you could be in auto mode and use your thumb to + - shift. Also, the car is intelligent. If you are getting aggressive and having fun, the transmission will adjust and get into an aggressive mode with you. If you drive normal it will act normal. Also, at 6000 RPM's, it sounds like it shifting up to far. Try your manual mode and keep your thumbs on your + - shifting and see what happens. When I get aggressive and really slow to much into a turn, sometimes the TIP will shift down to 1st and is ready to rock out of a turn. Also, has the TIP had a full service...they drop the pan, replace the filter, etc. and replace the oil.
