I have an 06 dakota if you couldn't tell and im about to make a custom rear seat center console sub box. my main question is about down firing. my friends dad who used to install professionally said down firing sounds good in a small truck like mine b.c of "extended wave lengths and JL audio also makes a down firing stealth box for that reason." he said. and i definitely want a port on it.
Down fire is definately the way to go. Your friend is 1/2 right, now for the other half. As boxes get small, the box tends to peak at higher frequencies. The obvious fix would be to make a larger box. But in many cases this is not posible. By down firing you increase the front loading of the woofer. The loading helps recover some of the low frequencies that are lost due to small box size. And it works. Porting, even better I built a downfire for my wifes car, it works great. Wife Down Fire Box