if your gunna put a 15" in the trunk here a box i designed its 3.8 cubs tuned to 32hz with 50 sq in of port
was gunna have a 15" dc level 4 but the day my money got on paypal i got into an accident and totaled the car (i miss that car never had any problems with it at all and it was so fast compared to my truck i have now )
heres the RE page and a scetchup of it