[AceX]

I'm showing with a bunch of trucks right now that have this sort of mod done. It's called a blow-through and requires alot of work and calculation to do properly. The biggest benefit of course is going to be monster bass thanks to the added room you will have for more equipment.

I'm not against them, but I don't recommend them unless you are going all out with the truck as far as audio/video is concerned.

You can get some awesome sound from shallow subs from Soundstream, JL Audio, Pioneer, Kicker, and others.