Can you tune the bass frequencies in the cabin.

IDK if that title is correct. This question may seem odd but I've found a fairly annoying problem after I installed a sub / amp in my '07 Crew Cab.

I used this box built for the truck
http://www.sonicelectronix.com/item_89323_Bbox-by-Atrend-A131-10CPV.html

I had a JL audio 10w0 v2 from my old car that fit in the box without issue hence I used it. I realize it's not an ideal sub for the box but it fit from a depth perspective and I already had it so that's the way I went. This same sub / amp combo I'm using performed almost better than I expected it to in my old car, in a square ported 1.2 cf box in the trunk of the car.

The weird issue in the truck I think is more box related than anything but wanted your feedback here if i could please.

When seated in the drivers seat it seems like the bass frequency completely misses me. If I move forward in the seat, sit in the back, whatever it sounds and hits fantastic. But where I sit every day It's like I completely miss the soundstage for the Bass. Not sure if it's a product of the port out the side of the box or what but I'm curious if there's any way to change this. I literally drive around leaning up against the wheel and I'm perfectly fine with the sound. To get better bass in my seat I've had to turn the gain up pretty high on the amp which makes the Bass completely over the top to others in the truck.

Ideas on this? Am I going to need to go to a custom box to solve this issue?