I’ve just added brake cooling to by E86 after turning the sidewall of my front left PS4 into bubble wrap on a track day (pic below). Tyre burped air under high speed cornering then 4km trundle to the pits killed the sidewall. Cooling may help slightly but I did this mod more for the fun of it.
Both this guide for the facelift and the other on here for the pre-facelift have been very useful but I have done things slightly differently and learnt a few lessons to share.
I opted for inlets in the bumper to benefit from ram air pressure as well as air velocity. I used Revotec 51mm (2”) aluminium inlets as these were the largest I could fit with minimal butchery to the bumper. These inlets came with double sided sticky foam to attach them. Even though i removed the crosshatching with a dremel to smooth the surface, they did not stick for long so I used 3-off 3.5mm bolts and washers instead.
When cutting the bumper, be aware that you’ll have to remove some of the fog light mounting bracket. It’s pretty chunky so I doubt this will have an effect. Be careful with the bolt placement.
I used double skin silicone air ducting. 1.02meters per side. I’d ordered a 2m length. Luckily it was slightly longer as I needed those extra cm’s. I’d recommend ordering 2.2metres.
The hose has to pass through a plastic wall. This was easy to cut with a 64mm hole saw. To prevent the sharp edge to the plastic wearing and eventually cutting the hose. I bought some large rubber cable grommets. Yes, you can see in the picture with the horn that I bought the wrong size of grommet and had to cut it to open it up. Silly me.
The horns block the hose routing so I had to move them upwards by shortening their brackets by about an inch. Easy job.
The stock dust shields already have a hole to let air into the inside of the brake discs. There are lots of folds in the dust shield but Revotec 51mm outlets fitted perfectly between these. I opened up the existing slot and attached with 3 bolts.
The hose attaches to the inlets and outlets using jubilee clips.
All in, this cost me around £85. Very happy with the result. I’m still toying with fitting black mesh over the inlets to make it more inconspicuous but this would heavily affect airflow. So far, I’m happy with them as they are.
I think the easiest way will be to fit the cooling ducts then to make test runs with and without bath plugs in the sink waste pipes :lol: 
