tuning radio

Pioneer radio has subwoofer setting that has 50 63 80 or 100 hz. What does that mean rite now I have my 2 15"s at 80hz on the radio What is each one.(The Great)

Those numbers are the different crossover points for your subwoofer. 

Choose the setting by experimentation and consideration to the abilities of your mids.  You would have to have some big front mids, like 8", to use a lower setting such as 63 Hz.  That's a little low for most 6.5's to keep from pushing them at the lower extremes.  And, if you use the deck's sub crossover, set the sub amp's crossover off or to its highest possible Hz setting.Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.