Your 18's sound like 18's. If you followed ed's desing criteria for a small sealed enclosure they might sound "crisp and clear"

 

What type of music do you listen to? That determines alot on what your setup should be. Ported boxes are USUALLY for rap, etc. Sealed for the rock, techno stuff, this is the first time ive heard get 12s for techno. Nowadays i see alot of guys goin with 2 10' subs in a ported box. IMHO this is a great setup, you can get the thump and they can still have that punch for rock. The other thing is can you fit the box in your hatch(im assuming its goin in the foxbody). Dont let the smaller subs fool you, they can bump hard, ive got a buddy with 3 JL w1's...its sick how good it sounds.
-lr

 

My sarcasm is very dry and almost stealth like at times

 

PREAL is on the ball with this one.
As for what kind of enclosure to run it depends ON THE VEHICLE NOT THE TYPE OF MUSIC. To make it simple, its like this - open cars (foxbody hatch) NEEDS to have a ported box, because you share the same air space as the speaker itself. A car with a trunk (sn-95), should have a sealed enclosure, regardless of the size of the driver (subwoofer). In a closed car the trunk acts as secondary enclosure , it helps resonate so you can hear it clearly.
As for the tone you want it to resonate at, that is determined by the cubic feet of space inside the enclosure and the size of the port (if it has one or more). I run 2 kicker comp 12's at 1000w each. Each one is sealed of from the other (to prevent distortion) in 1.75 cubic foot. My ports are tuned to 45hz, which to laymen is the low booming bass. Since rock hardly ever hits that low, metal and rock and roll sound REALLY good. But I can still listen rap, techno, house, etc. and itll sound the way its supposed to. If I had a sealed box, it could not resonate, (no boom) and IMO would sound like absolute ****.
-P.
PS: Look at the woofer as a drum, the larger the diameter the lower it can hit. But remember humans can only hear to about 20 hz, so going too big is pointless.

 

Thats a load of crap from P-Zero. I play my Sony's at 3Hz all day (some days I drop her down to -5Hz). Took it to a dB competition and they cant even measure it. It's that crazy.

Xplods... Got to love them.

 

Holla, I never seen -5 hz before. I bet that is a trip. Shoot, I play 3 hz signals all the time, I love the way they sound........lol

 

The difference between the two is 2 inches

 

That was going to be my original response but I thought i'd help out some this time.

 

thanks everyone for the info. i just bought 2 12' kicker cvr. im planning on building the box myself so how would i go about making a ported box? where should the port go and how big?

 

Slot ported, dont do round PVC tubes. It's simple. And honestly just google something if your lost on how to make a box. I would suggest using 3/4" MDF all the way around sometimes I see people use 1/2" all around and I also see them use it everwhere except the side which the woofer is mounted to. Same $, space (if an inch or less is crucial).