15" sub

I have a 15" Rockford fosgate p2 and I built a floor where the spare tire goes and you can barely hear the sub. I do not know what else to do to the thing. This is my first time building one so any help is needed!

Product: JL Audio 15W6 Specs: http://mobile.jlaudio.com/pdfs/15_18W6_BDS.pdf Description/Condition: Pretty much brand new. Has less than a minute of play on a home theater amp free air. No physical damage or blemishes whatsoever. Sub has been sitting in a factory plastic bag inside original...

First off- I have tons of refs on ca.com and ebay same user name. Up for sale are 2 custom 15's built by team psi. Only for sale due to me getting a bigger amp.Work excellent and will be packaged properly. They sound good and get fairly loud. I need these gone soon Dual 4 ohm handle 500 rms...