dont let me spoil the fun. im still more than willing to deliver this amp to gibbys.but it would have to be before noon

 

Don't go sticking a 400w sub and a different JL sub together. It'd be cheaper (maybe - $40 for everything is a steal) to buy a 15" (2-10" = 157 vs. 1-15" = 176 cone area) and use 2-2.25 cubes. A sealed 15" on 500W is plenty for rap and rock if it's in the right box. My second sub was a Kicker CVR 15" in 3.5 cubes on 220W and it was great while it lasted, I got a Kenwood 550w amp and a 2.25 cube box and it was so quiet. I bet a Digital Designs 8" on 500W in a ported box will own 2 sealed 10's on 500W, there's your trunk space.

 

^^^ Agreed.
I didn't see the earlier suggestion about mixing subs. Not a good idea. In general, the only good time mix subs is if you're getting different sizes and crossing them over at different points ie - one plays 40 hz down and the other plays 40 - 100hz, or a similar set up.

Mixing subs will likely create goofy cancellation issues, as different subs peak at differences and respond slower and faster at different frequencies. These changes will cause the subs to be momentarily out of phase with each. The greater the difference, the worse the cancellation.

You might be able to get away with it. There is currently a thread open in the install related forum in which a guy has 2 Apline type R's and one Apline Type X all running together. It works . . . but I suspect the reason why it works is that being all Alpine, they are fairly similarly built.

Don't mix subs. You're better off with one sub instead of 2 mis-matched subs.