Dd 9512

Looking for some input on design I came up with using online tool. I have 2001 Tahoe so I have a lot of room. The specs are as follows:20"x32"x13" (inside dimensions) Total inside volume: aprox. 4.26 cu ft Round port: Port area 28.27 in2 , length of 28.98" want the port 4" Away from rear firing back with sub up. Dont know how to make actual design on computer but can probably draw it out. What ya'll think??:dontknow: but I am hoping I am on right track at least. Much appreciated. Thank you.