This custom cold air intake was based solely off the design by Chuck Brazeau. I would suggest following his steps and instrcutions listed at this website: Intake link. The cold-air intake is for the stock M3 HFM that is 3" in diameter. I followed Chuck's design although I did change a few things to suit my car and use. These were minor changes but useful.

1: Chuck relocated his horn somewhere inside the front bumper. I removed my horn completely, for I often hit the horn on a hard turn unintentially. Plus do you REALLY need a horn? To the right is a photo of the area where the intake will be moutned. This was where the stock-air box was located. One thing to note is that I removed the cruise control, which isn't a step for the location of the cruise control is safe.

2: I adjusted the HFM location to angle more towards the outside. This way there is more room between the engine and the intake pipe. Keeps the temp down on the pipe. The rubber intake coupler attached to the HFM is not secured and flexable, thus making it easy to adjust. The picture to the right is after the intake is assembled before it gets painted.

3: For the brake-duct flap: I used a 10mm x 3inch bolt to secure the flap cut and bent for the air flow redirection. Also used 2 inch washers on the outsides of the duct to provide a stable mount. The picture shown on the right is the completed intake after paint. The air-duct picture will be online soon.

4: I lined the sharp metal edges where the air filter sets, with a thin layor of rubber. To prevent and damamge to the filter from the sharp metal edges. If you look closely around the air-filter in the picture located to the right, you can see the black rubber. Also note the angle of the pipe coming from the HFM.

3.5" Cold Air Intake

Chuck listed the parts on his website for the 3.5" intake, but has not physically constructed the intake. After some work and searching for parts, I was able to build the larger CAI for the larger HFM. Mine in particular was for the HFM from a 540i.

The differences with the two intake procedures is with the specific pipe parts. Please refer to the original document for the majority of the procedure.

Parts list for 3.5" intake - K&N Filter (4 5/8" diameter, 7" long, cone shaped) - Part# RU-3130. This fits better than the 3" air filter - 90 degree Aluminized 3.5" pipe from AirFlowOnline, part# 431-350PE : ~$23.00 - 3" to 3.5" Aluminized exhaust pipe adapter from AirFlowOnline, part# 4315-335-3PE **** Cheapest adapter, most are plastic and cost over $80.00!, this is $10.00 3.5" Intake pipe rubber hose couplings - Part# 50350-10G-200, Purchased from Hose Techniques. You will need 3 of them. - 6 aviator hose clamps, 3" to 4" diameter