Cerwin Vegas need air?
 

I've got Cerwin Vega 6" round speakers mounted in the rear shock tower in that black tub that came in the car. they seem to make alot of "thump"ing bass, but not really good with pitches and actually making musical bass. Just wondering if that could be because there's no port in the tub. I thught about cutting a 1-2" dia. hole in the tub to make a port, but if that made it worse, I didn't have a way to fix it back without buying new tubs. Any suggestions?

try this:
remove the bottom of the tub and just mount the lid with the speaker. if that makes a difference then you might want to port the tub. if you're using the stock amps and wiring you might have to make a temporary extension so the wires will reach the speakers.