I have a audiobahn aw1500 15" sub, it's powered by a usa-100. Right now it's pretty loud in the back of a cargo van facing the passenger corner. It's in a 1.6 cu ft sealed box right now. Do you think I would get a significant volume increase if I went to the max recomended ported box 3.5 cu ft? The amp puts out a "rated" 315 watts @ 2 ohm mono. The sub is 800 watts rms. Please keep in mind this is a wide open cargo van Ford E-250.