Audio Systems: subs, mtx 7500, db increase

Question
I have 2 12" mtx 7500 subs in an enclosed box, i was wondering how i can make them louder outside the car, do i move them back closer to my seat or do i move them closer to my back window( by the way I have a 1996 jeep), all i want to know is how to get them to sound louder outside the jeep?

Answer
It takes more power and the input level cranked up.  But feeding through the metal and glass in a car is not an easy thing.  It does take lots of power.  If you want the sound to be heard on the outside, roll the windows down and place the speakers near the window!  Really.  

My experience is that what most people want is for the bass or low frequencies to be more audible.  That is where the power is needed.  The bass subs take exponentially higher power to produce small changes in acoustic level.  For example, to increase the level so that is sounds, to the ear, about twice as loud takes about 10 time the electrical power input. This is due to the non-linear hearing characteristics of the human ear.   That is why we use the db or decibel as a unit of measure for sound pressure.  A 3 db increase in power input will produce an increase in acoustic power output just enough to hear the difference.

So, to some extent you are fighting mother nature. The show cars that you have seen that pump out whole neighborhood sound are using big kilowatt amps and sub woofer mounted near the edge of the back end of the vehicle to pump out spl to the whole city.

I don't know the mtx 7500s,, but you may need something stronger with higher sensitivity readings and really big amps.

Hope this helps.
Cleggsan