The one on top of the opti goes into the elbow like in that pic (fresh filtered air at atmospheric pressure) and the one on the bottom goes to vaccuum on the engine from the driver side of the intake like halfway down, there's a T fitting there. Essentially using vacuum to draw filtered air through the opti.

 

So its a 1/8" hose from the elbow but the cap vent is larger, the pic shows a larger piece? Can that be purchased? Or whats the best way of cobbling something together?

Thanks