SQ subs on the other hand will be bit expensive & start upwards of 10K approximately. There are many brands again like Rainbow, PHD, HAT, etc.
Honestly you've to do 2 things. Fix up your budget, then audition the ones you shortlist.
Subs hitting hard may be nice to have, but prolonged listening in the car will not be likeable (in my opinion). Due to the dynamics of the car & the small area, you can hear those boomy bass for a long time.