Port location

[Inoevenkea]

Ok right now i plan on building a box in my 2000 4 door jimmy. I got a solo x 18 that i am gonna put in the back in a box thats 36" wide 24" high and 22" deep and planning on tuning it to 35hz. I'll have the sub firing forward and would want port forward. I had subs up port back for a diffent setup and wanna try something different. I know if i put the port on the bottom firing into the back seat it wouldn't have that great of an output correct? I am going to be building a 6X9 rack for rear fill, do you think it would be good to put subs front port up? I just need some info on if there is a difference on where you put your port whether it be on the front top or front driver etc.? Thanks