anybodys guess

If you are trying to get loud only then you need to find the loudest resonant frquency of the vehicle and then tune the box to that frequency. A ported box is the only wa to do this and generally will give you a gain of 3 db. The other person had a different vehicle, thus it cannot be compared at all.

whats up bro i would definatly go ported if i were u .

with that other guy hitting only 4 tenths higher.....there could be a # of different reasons why....he could have built the box wrong, bad charging system, maybe even or more of his subs are shot, amp maybe shot, he may not have played the right frequency.....

there are plenty of things to take into factor. but i definatly think u should go ported. as long as u build it right u will 100% gauranteed hear and see a difference.

if u have a few minutes take a look at my sounddomian page below.....if u scroll to the bottom pics, those were 4 12" L7 subs ( when they first came out ) with 2 kicker zr1000 amps. when i competed  with that system i actually removed one amp and so i had 1 zr1000 going to all 4 subs and i still hit 152db. so with 4 15's in a wall u should in theory demolish my #'s.

dynamt will definatly help too....put some on the roof and door to stop flexing...every DB counts when u are competeing whether it is a tenth or 1.

goodluck, let us know how it turns out.