Proper way to down shift?

ChipsWithDips

In that case all you need to do is click that paddle when your rpms drop too low. What is too low? Depends how you are driving. If you are WOT racing, then you want to keep the rpms in the upper end of the rpm range, above 4 or 5k. If you are just cruising at a constant speed around town at light throttle, just keep the rpm above 1.5k. Running below that can put a lot of stress on the engine or stall out.

Downshift when you want more power (horsepower is more-or-less directly related to rpm). If you're already at 5k rpm you probably don't need to downshift(i doubt the AT will let you overrev the engine from a downshift anyways)