is the pro design aluminum plate that holds the filter in place soley for that purpose or does it increase air flow or air direction? what about the one from yamaha biggy was talking about in another thread?

 

The primary purpose is to hold the air filter and provide a superior seal for the filter to the airbox. As an additional benefit, the airfilters that are used with the adapter are of a higher flowing type plus the added ability to remove the airbox lid for even greater gains. I don't know for sure, but I would not be suprised if the Yamaha adapter is made by Pro-Design. The Yamaha GYT-R clutch basket and pressure plate are made by Hinson.