i want to put one of these systems in my jeep grand cherokee. an 18" fi btl powered by a hifonics bxi 1606d in a 8 cu ft ported boxed tuned to 30 hz and then later on upgrade to an mmats d3000.1 and also a stronger charging system. or 2 15" fiq's powered with two bxi 1606d hifonics amps. (would i still have to upgrade the charging system?). i know it is hard to tell, but do you have any idea which would be louder ?