Ok... Got the above subs. Want to port the enclosure rear-firing subs and ports (preferably), for an suv. They will be on a single amp, so I guess they need to share a single airspace and port. Suggestions? Never done the calculations on porting multiple subs so not sure how to even design it to specs, or where I should start. I have enough room to have them in-line but i'd probably need the port(s) to go on the top or bottom and i'm not sure if that's best for stability of the box. Materials will be MDF.