the relationship is a funny one. box is only one thing which works in combination with other things - cone area, port area and power, to influence the peak note.

in Dave's rex with 2 12's on 2 amps with a box that's like 2.9 cubes the car peaked at 56hz. so that's like 1.45 cubes per driver, and about 85 inches of port area.

So we had 226 inches of cone / 85 inches of port = 2.65 (ratio of cone to port) - peaking at 56hz

but then with the same 2 amps BUT 4 12's in a box that's 3.7 cf with more port - 0.9cf per driver and 100 inches of port the car peaked at 54hz.

Here we have 452 inches of cone / 100 inches of port = 4.5 (ratio of cone to port) - peaking at 54hz

another good ratio to play with is port area to box volume.

really the best way is to test over and over again while trying different boxes, etc.

if a car is deadened right you can get 0.5 to a full db gain just from deadening.

My rear hatch is what pushed me over the 150 mark gaining a little over 0.5 db. Funny the way it works because your score tanked when you deadened the hatch in your jeep.

i believe i had not done it the right way. Dave i wish you were closer to us, you seem like a good person to test with.

Wouldn't having 2 more woofers affect peak frequency more ?
Just thinking out loud...if you would have doubled up the first box, would the peak have been 54 or 56 ?

In the Jeep (spent way more time testing compared to the car in the first post) seems like my peak frequency is 50hz all the time with the BTL 12. With all box volume and port area changes it didn't shift up or down.

Now speaking of deadener...I have 25 square feet of Vibraflex to go on the roof of the Jeep. Thoughts on Vibraflex vs let's say Dynamat extreme ?
Also, what would be the right way to apply and test ?

Doesn't even compare. Vibraflex wins all the time. Wish we could get some stuff like that around here at reasonable prices.

I'd gladly send you guys some if we can find a cheap shipping option. Bought mine because I found it dirt cheap.

i find it's more in how the deadner is applied. as long as it sticks well.

i would not bother with the roof.

put it on the inner skin of the front doors, covering every hole.

my jeep varied between 48 and 52 hz depending on how much cone and power i used

1dB is still a whole damn deebee :)

Maybe you car sucks, do you have more pics of it? What is the difference dash/floor?