Ive got 2 maw 15 subs and need to build a box for them in a trunk car. Ive never built a box so i dont know what dimensions would need to be and all that. The company reccomends 3^ft ported tuned to 30 hz. How would 8^ft ported tuned to 30 hz for 2 of them be? Id like better lows on songs like lil jon - bia bia for example. Running them on a hifonics amp giving them 600rms each.