I was wondering the same as well as I don't think there is enough space for me to do this with all the plumbing from the GTM Stg2 SC intercooler and oil cooler.

If routing air from the undertray, a lot less tubing needs to be used it just goes from the control arm area to the brakes, effectively bypassing the inter cooler and oil cooler locations.

Check out: Brake Cooling Options

And pay close attention to the 'Scoop mounted to control arm'. You can route a hose to under the control arm, and on track days when you do not have to worry about clearance, you can simply attach the huge scoop (to make up for the low pressure area) to the pre-installed hoses.

Great write up, I am in the middle of trying install a brake duct kit for my 370z as I'm gonna track it at Laguna Seca next month. Where did you get the Aluminum Flange at? Most of the ones I found has 2 rivot flanges that extends out of the circular shape. Link

I don't know if the brake dust shield will have enough room for this particular shape.

Aircraft spruce aviation supply company.

I'm in the process of doing the same thing...
http://www.the370z.com/diy-section-d...tallation.html

My DIY is more of just plain pictures but I'll update you guys when I'm done. I decided to go with 3" Diameter...a little overkill, in fact now i'm a little worried because more cool air will get exposed to the surface than the inner hub of the rotor. Oh well...maybe I'll design something else like a tray funnel style one day.

Also, have you taken any temperature? Stillen's website (essentially the exact same thing) claims 25% drop in temp, but I noticed they put a Stoptech brake setup. Who knows if that claim is really true.

Pardon me for the thread revival. I'm going to be doing this brake duct mod next weekend and wanted to say thanks for the write up. But, what is this "ice mode"? I searched but didn't find anything.

I completed my DIY brake duct kit this weekend and it turned out great. All in all this cost me about $70 for hose (which I had too much of), flanges, clamps, and a rivet gun because I didn't have one. Big thanks to ResIpsa for creating this thread and paving the way for those of us looking for a DIY solution for brake cooling. Mods, can we make this is a sticky?

I took some pics that I wanted to share so others can use them along with ResIpsa's. I used 2.5 inch ducting from Amazon Hose and 2.5 inch aluminum flanges from Aircraft Spruce.

This is the drivers side. You can see all it took was cutting a hole in the fender liner and routing the 2.5inch hose through the hole. We had to flatten out the hose as it ran along the inner fender liner so it wouldn't rub, but it would still flow a good amount of air. T=You can see where we zip tied it to the frame as well:

http://i853.photobucket.com/albums/a...pszqvezjwx.jpg
http://i853.photobucket.com/albums/a...psc0inwmvi.jpg
http://i853.photobucket.com/albums/a...psxiqtrmde.jpg
http://i853.photobucket.com/albums/a...pslofuazz3.jpg

Then, we cut a circular hole in the dust shield using a hole saw and riveted the aluminum flange to the shield:
http://i853.photobucket.com/albums/a...psyzb2rp0v.jpg
http://i853.photobucket.com/albums/a...psqltf2yan.jpg
http://i853.photobucket.com/albums/a...psjdqxhq4m.jpg

The passenger side was tough. We had to squeeze the tubing through the small area between the washer fluid tank and the radiator support. You must trim a small piece off the radiator support to allow it to fit. I didn't take a before picture unfortunately, but you can see the area that was cut in the first picture below. Then, we cut a similar hole in the fender liner like on the driver's side and flattened out the hose to avoid rubbing:
http://i853.photobucket.com/albums/a...pshyude7co.jpg
http://i853.photobucket.com/albums/a...psoexh6220.jpg

Lastly, I used a dremel to cut out the rigid portion of the vent insert things and affixed the flanges directly to the removable plastic piece. This way I wouldn't be riveting anything directly to the bumper and cutting holes in it and whatnot. You could do it any way you like, but the less permanent damage you have to do the better, I say:
http://i853.photobucket.com/albums/a...pst5ifirbi.jpg
http://i853.photobucket.com/albums/a...psu2lqrq1x.jpg
http://i853.photobucket.com/albums/a...psloacuffx.jpg
http://i853.photobucket.com/albums/a...pshicpt93i.jpg
http://i853.photobucket.com/albums/a...psw9gknfyh.jpg
http://i853.photobucket.com/albums/a...psjtocavyh.jpg

All in all it was easy to complete and definitely flows air. We held a little fan up to the hose after it was all fitted up and plenty of air was travelling through it. It's hard to believe people spend $300 on a kit from Stillen for this.