In a sealed box does the b above -3db point affect the lower b?

the smaller the box the more of a bump you creat in the 40-50hz range. add that to the cabinet gain of a vehivle at that range also and you get loud annoying b. the smaller the cabinet the quicker a speaker will roll off and get rid of the lowest frequencies(which in my opinion are the most important for a "sub".. its not a stand alone woofer but thats what they usaully turn out to be in kids cars. oh and eq's eat tone and power.