anyone here have any experience in building blow through boxes? i have a 2006 gmc sierra 1500 single cab. dont really have the room to throw in some nice subs. so i was thinking about making a blow through box. is it possible to build a ported blow through box? or does it have to be sealed? and if anyone knows where i can get some information and some pics on cuttin the back wall and making the box and everything would be greatly appreciated. i am thinkin bout gettin two 12" earthquake subzeros with an orion 2500d amp. any help would be awsome!