Audio Systems: Sub Enclosure Modification, exact model number, ported boxes

Question
Hi, I currently have two kenwood speakers 700W max a piece, I also have them in a sealed box with the dimensions H-15in x W-30in x D-12in.  I drive a Tahoe(SUV) and want to know if I should add portholes to my box, and the type/size.  I listen to mostly hip hop and reggae.  Thanks for your help.

Answer
unfortunatly, that's not goign to really work.  ported boxes need to be bigger than sealed boxes to sound right. by the dimensions you've given me it works out to about 1.15 cubic feet per speaker which is fine for a sealed box but a ported box usually is around
1.5-2.5 cubic feet for a 10"
2-3 cubic feet for a 12"
3-5 cubic feet for a 15"

also the port itsnt just a hole in the box its a tube, the length and width of the tube verses the size of the box all play a big part in the sound it makes.  with how small this box is you'd have a very hard time even fitting the port tube inside it.  and the port being in the box technically takes up even more space, so your 1.15 turns into 1 or so!
you really need to build a new box to move them into a ported environment.  I'd be happy to help you build one.  in fact If you give me the exact model number of the subs I can plot graphs of how they sound now verses how they will sound in their new box. tell me the amplifier you have as well.  If you want me to do all that just reply to this (privately) and give me your email address, and we can get started!