Ok so i got four of the 21 inch i.a dp's and im not sure what size or style box that would get the most out of them. would it be better with subs up and port back or in a wall either all the way back or right next to the b pillars. keep in mind this is going in an astro panel. also would they be better in an 8 cube box or 10 cube box. i like low bass so im pretty sure ill do a port at 32hz but size im not sure as ive never had 21's i have two 18's in now (audioque) and they are loud as hell with subs up port back in 12 cube net tuned at 35 hz please give me some opinions on what to do

any feedback at all would be appreciated

I would shoot iamamp3pimp a PM with this question. He has a good knowledge of these subs.