airspace for DB6500

Systems

I am building some fiberglass speaker pods for my new polk 6500 components, but cant find out how much airspace to use for the 6 1/2, does anyone have an idea, if Polk doesnt have a recommended amount what is the average for a 6 1/2 speaker, thanks!

Also just from messing with them they sound kinda bright, any one have some recomendations besides "ADD MORE BASS"

Thanks!

PoweredByDodge

.13 - .15 i'd say.