More bass?
I have the in dash 6 cd changer Monsoon system and usually have the bass at -3
I did crank it up a couple of times to see what it could do and my 9 year started yelling that his seat was moving

Now my kids yell "turn up the thump". I see no need to add or change out that rear bass, the whole dam truck shakes when it is turned up.
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Black, LUX, Ebony/Morocco Leather, brushguard, crossbows, 2 A-1000 Vizualogic tv/dvd, game connections, 35% tint