I think they are about 8 inches or so deep, I'll check soon.

I'm not sure how they sound with 500w/ I can tell you they rock at 200w/. Ultimately I think all that matters is how many liters they displace at xmax and at what THD. You'll have a hard time finding a better driver. Efficiency is a nice bonus so that you headlights don't dim at idle, or worse, while driving.