Sound Upgrade

So I've seen the tweeter swap a lot and I was wondering if anyone has experimented with a shallow down fire sub under the seats or swapped out a sub somewhere.

I'm not looking to rattle the neighborhood, just looking for some extra bass. Not sure how things work with the stock head unit or if its possible. I used to have a Bazooka tube in my jeep but doesn't look like that shape would fit anywhere in a double cab. Thanks in advance.

 

OEM Audio+ makes a dual sub setup for behind the rear seats in the double cab. Taco Tunes makes a housing for the same spot. You can custom make a housing

 

That set up is actually really cool; I like the sub box and the ingenuity. Might have to save a bit more with that price tag. I havent really bought speakers for a while, it was quite a shock.