I will be building a box for 2 Sundown E 15s. The subs are dual 4ohm going to wire them to 1ohm on a audiopipe AP10001D. So they will be gettin a little more than rms wattage but I dont see that being a problem. Thats where i need help. I know on Sundowns website they recommend ported 3.0-4.0ft^3 @ 35 hz. What would yall recommend on box size and hz since i will be overpowering a little. Subs are going in a 2005 Silverado crew cab z71. I have the 60/40 sectioned backseat. I will possibly removing the 60 part for box. So pretty much what i need to know is that: ft^3 size/hz level SIngle chamber or dual? Daily application not sure on dimensions of section on backseat but i can measure tonight Also which direction for subs/port. Ive always thought subs up hit hardest in a truck but not sure where to do port. Thanks!