I've the the Breathless Stage 2b kit. The towers came with the kit, and they come with a stencile. You simply pop your old towers off (they pull right off) and put these ones on. However, if you want them "functional", BPP sends you a cardboard stencile that you place in the middle of where the tower goes, outline, then cut out. Now it'll send some air into your engine bay. I didn't bother making mine functional, it won't make a huge difference, and just lets more water get in there. I wouldn't have bought them seperately either, they just came with the package so why not just toss em' on. They do look good though.
2003 Sunset Metalic Orange H2 - Breathless Stage 2B, HID's, Gobi Rack & Ladder.
2003 Millenium Yellow Z06