HRT STPR

I have 3 12" Cerwin Vega 124's. I just rebuilt the box for the fourth time, and i was just at a car/bass show, and i got to talking to some people and they told me that my ports are way to small. The subs call for 2.0 cu ft and a 1/2x11" port. i made the box a total inside open air at 7.3 cu ft, and 2 ports 2 1/2x11". Need help with a new design yet again. was thinking of doing subs front (like have now) at the back seat, and port all the way at the back. Need to know what size port you think i should use. Should i make a slotted port, or the Aero ports? As it sits, i still have Very LITTLE excursion and AIR MOVEMENT. also what hertz should i tune it to for best results, and how do i tune it? i know its a lot of questions, but its all stuff i want to learn. I did a quick Term Lab for shits and giggles, and i hit 138.1 DB with a small amp, bad alternator, and an apparently small box. Any and all help is greatly appreciated. Thank You