Need help with box design for 1 15 inch old school SX (PSI recone)

[dnb1982]

New poster here wondering if I could get some help designing a new box for my old school 15 inch Re Audio SX. The sub was reconed about 5 or 6 years back by David of PSI (not sure if that makes a difference).

I have a maxium of: 36 width, 30 depth and a height of 30.

The sub will be in a 2002 Blazer Xtreme and ran off an old school Viper D1200.1

This is just a daily driver that I would like to sound as clean as possible. I listen to mostly rap/hip hop, electronic music and a little bit of rock.

My current box is for two SX 15's (recones from PSI) and the subs are facing up and port firing back. Would I be better off with the subs up or facing the back? The dimensions were: 36 width, 23 deep, 18 height with a 3 inch port that is 19.25 deep. Both subs were in the same chamber and the box had zero extra bracing with a single baffle. It sounds like complete crap when the sub tries to go low. A friend had built the box, but I have no clue where he got the specs. He said it was tuned in the range of 33 hz? Not sure if those calculations come out right.

I figure if I am not happy after a new box with a single sub, then I will switch over to a Sundown Audio SA 12 or 15.

[dnb1982]

I would also like to have the sub firing up and port firing back.