I am looking to add some bass to my 13' G37 Sedan. I don't have much of a budget, about $400 USD. I listen to a variety of music, Rap, HipHop, Rock, EDM and such. I do like deep bass. My biggest issue is space constraints. 27" wide, about 17" deep, and 17" tall. Also, what would be better for my situation, 2x 8"s, or 1x 12"?
A 12" sub will generally reach deeper with less strain (excursion) than 8" ones. You need to make some basic decisions regarding what you want:
Are you interested in building a DIY enclosure? Prefab? High Q? Low Q? Would you rather just put some speakers in the rear deck and run them IB (Infinite Baffle)? Are you after stronger bass, or lower bass? What system is in the car now?
Is there an opening from the trunk to the car for the sound to get through? If your trunk is well sealed, IB is easy enough and will improve your sound with a modest amp and a couple subs designed for such use- but will not likely win any SPL contests.
I prefer bandpass enclosures ported to the cabin and concealed electrics when the car is for general use and you want to retain use of the trunk = no exposed woofers to get damaged, and you can control the tuning/woofer excursion fairly well with a simple BP4 type enclosure. Takes thought, planning, and careful execution but can come out really nice without too much $$.
WinISD is free and not too difficult to learn- spend some time modeling various woofers and boxes, it's fun! BassBox is even more fun but you have to pay for it.
Saw an intriguing prefab bandpass for super cheap the other day, I could not build it for the price.. check out the Dual BP1204. Not really my thing, but looks pretty plug-and-play to me. }