Subwoofer dilemma

[36jere]

So I have a Challenger with 485max output alt, 350@idle, big 3, 3/0 power wire from alt to rear battery, smart 5 bass for my power but I'm unsure of which subs I should run. I have 1sundownx15v3 now, not installed but I could buy one more and run the 2, or I'm thinking about 2sundown  zv6 12's or lastly maybe 4 sundown  sa12's. I listen to bass heavy music mostly rap. Whats your opinion on what would sound better. I currently have 2 synergy wfo 12's installed and they sound alright but not that impressed and while removing them recently was carrying one with one hand and the basket cracked and broke in 4 places( they weigh 80lbs each). So planning something new any replies would be appreciated.

[Joe X]

Post max dimensions for a box and if seats will fold down.