one of my friends did one and it was 1 10" jl w3 in the console. he kept the whole top peice where is folds up for a seat and down for an armrest and storage. he fiberglassed the bottom and formed it just like the seat then he covered it with some foam for padding. it looks just like the factory seat but there is a sub in there. if you did that and kept the subs you have behind the seat it should sound pretty good. just mount your amps underneath the back seat. downfiring a sub is actually one of the best ways to get alot of sound out of a sub.