I have 2 12" MTX Thunder 4500 subs in my Toyota 4Runner. On songs that have low notes like "Put On" by Young Jeezy, my subs cant really hit some of the low notes. On the low notes, they're moving but they aren't producing much sound. Is it because 12s cant hit lower notes and I would have to upgrade to some 15s or 18s? Or is it because I dont have a good enough box for them? Or what? Any help is appreciated.