[Ryfly05]

Ok.. Well the "proper" way to downshift for a corner is to do the downshift as soon as the rpms drop enough that you can go to the next lower gear without over reving the engine. So to do it perfectly would be to hit the exact red line of the engine on the downshift. If you need to go down another gear, you do the exact same thing again. This maximizes engine braking, slows you down faster and/or can save your brakes a small amount.

At the level of us poor schmucks doing trackdays and hpde's does it really matter? Probably not, but that doesn't mean you shouldn't try to do it the "proper" way anyways.