lets see the pics of your sub box, preferably under the seat and with 10's. put the diminensions also and the amount of air sapce you have.

i have a 04 supercab and would like to put some subs under the back seat so please help me out

 

You might ask a mod to move this to the Speakers and Subwoofers section; you will get more replies there.

 

http://www.supercrewsound.com/commer...dId=9&catId=58

Thats the one I use. I have a 10inc JL Audio in it. Sounds perfect!