enclosure help with sundown x8 under the seat

[dirtyduramax97]

Upgrading from my Sa-8 to the x8 last box sounded pretty good but did not have the thump I was hoping for. First time having 8's so mayby thats just it, hoping to get a second opinion on a box and see if its just poor tuning. currently running 2 Sa 8 off 1600rms. box is tuned around 34hz. Its under the seat in my silverado so very limited to space. I have risen the seats up so I can get these to work. Current box design is a wedge box which I have no way of changing. Dimensions were 0.625" thick 30" wide,17" deep,9.5" tall at the front and 7" tall at the back. Had a 3" port that was 21 1/2 in total length. Ive never designed a wedge box little more complicated then my usual rectangle design. Im trying to make a little more room for these new woofers. Im maxed out on width and depth. But I am able to go 10" tall in the front and 8" tall in the back. Im open to a round port if that would make more sence with the room I have to work with. Anyways if anyone has a spare few miniutes and could let me know if they think I could make these sound better by changing something let me know. Mostly unsure about port area and design. Im fairly limited to those max dimensions and wedge design.