help on a new setup

[chrisvia]

Last year, i asked for help on 18 inch re subs. And someone designed me a great box. It was in the cab of a Tundra. Now I am puttin it in a Cadilliac DTS. I dont think 18s will fit. Does anyone have suggestions on good deep bass, subs, ? I love 18s, but what can equal that? Everyone here has been helpful, thanks in advance. I'm pushing possibly 1000 watts with an R.E. ztx2 5000.1 BTW