Orion HCCA 154 SPL BOX help please

[Autumn]

I need help building a box for my Orion HCCA 154 Spl 15" sub. It's being powered by an Incriminator IA40.1 , the thing is I dont have much room in my car, I have a 2008 Volvo s40. I've tried two boxes both of which I had no part in building. The first one was ported but just didn't hit like it should, and the second one I ended up sawzalling the metal to my back seats l, taking out both front seats and center console, to get it in. This one just doesn't sound right. It's 9 ft3 without accounting for the speaker volume I believe, its 29.4 x 37.5 x 17 I THINK. the port is about 3.75 x 14 and yea it hits LOWS but it doesnt hit like it should at all. I feel like my two old school kicker solo baric 10s hit harder then this which that just ain't right. Sorry for being so vague, I just want to know what I need to do to make it where It's hard to breath lol. Thanks.