6" or 8" subwoofer for behind seat

[Pyrotechnic]

I'm trying to decide what I want to do for a subwoofer in my 77. The goal here is some good bass for listening to classic rock, alt rock, and country. I'm a drummer and play some bass guitar on the side, which should give you an idea of what my ears are tuned for. Drives me nuts when I can't hear the bass guitar.

I'd like it to be light weight. Space savings is also important too since I have hydraulic jack, CD changer, and speaker boxes behind the seat.

Looking to spend around $100 or less on the woofer itself but I will spend more if there is a particular product that really fits my needs. I'm open to a 6" or 8" woofer. I know the biggest thing is the recommend enclosure volume. Smaller is better for me. Mounting depth is important because there isn't a whole lot of room behind the seat of a 73-87.

Any recommendations ?