Air filter

Cold Air Intake - Make Your own:
The principle a cold air intake is basically to simply bring cool air from outside of the engine compartment and feed it smoothly into the throttle body. Most intakes also try to reduce on the restriction of the factory paper filter by using other types of air filter elements such as reticulated foam or oiled cotton gauze cone shaped filters.
You can build your own air intake kit at home from easily available plumbing parts that (in my opinion) is at least 95% as effective as a purchased unit. You can save some money by building this yourself, but I wouldn‘t place that as the primary reason for doing it~ This kit is 100% reversible and I can revert to stock in about 15 minutes.
Total time to build this should be less than 4 hours... Total cost should be less than $75.00 (Using a genuine K&N 9" Cone Filter). You can pick these parts up at Home Depot.
one length of 3" I.D. ABS Pipe (you only need about 7" but I had to buy 10 feet!)

two 3" I.D. ABS 45 degree bend fittings (1 Male end, 1 Female end )

one 3" I.D. ABS 22.5 degree bend fitting (female to female)

one 3" I.D. ABS straight joining piece (don‘t know the name for this... it is like a 5" piece of pipe)

one rubber 3" coupler with stainless band clamps (Actual inside diameter of this about 3.7" but it called a 3" coupler)

One grey PVC electrical conduit adaptor, size unknown (for now)... This is for the Emissions Control Hose, I brought the hose with me to the store to find a proper fitting piece. Please note that you will need to remove the 90 degree elbow off of the end of the Emissions control where is joins the factory airbox. You can remove the end of the hose by simply pulling it out! DO NOT CUT OR MODIFY THIS HOSE as this would prevent you from returning to stock in the future.

ABS pipe cement (get a small container you won‘t need much, ABS cement is extremely volatile, read the cautions and heed them!)
You will also need an air filter, I used a 9" K&N cone filter I literally had ‘laying around the garage‘. There is no reason you cannot tailor this project to use whatever your favorite filter is... If you build your intake like mine, with a ‘female‘ joint for the air filter you will need a 4" I.D. air filter to fit it properly. The filter I used happened to be a 9" cone with a 4" opening part number K&N RE-0870.
Other things you will find useful...
Epoxy Glue (5 minute epoxy is fine, JB Weld is better)
Sandpaper, multiple grits (I used 200 & 400 grit)
Dremel Tool or other rotary tool, also a hand file is useful for shaping ABS
Hacksaw
Paint Marker in a Light Color
Phillips Screwdriver
Flat Head Screwdriver
10mm Socket
13mm Socket
Socket Extension
Ratchet
The steps for this are basically the same as any other cold air intake for the Golf. You remove the factory airbox, remove the battery and the battery box. Finally you need to remove the fresh air ducting from behind the headlight area and (possibly, I did not) have to relocate some wiring. I followed the instructions for the EVO Cold Air intake (which is the one I would buy if I were purchasing a pre made unit).

Remove the stock airbox, battery and battery surround. I have removed the MAF for safety here

This shows the hole we will exploit to get the filter down low, behind the front bumper.
You will need to cut two pieces of ABS, one is 4" long and other is 7".  I cleaned the edges up with a Dremel tool, then sanded them for a smoother transition.

The order of assembly is (from Filter back)
45 degree with large (female) end towards filter (towards ground!)
ABS straight joining female to female piece (don‘t know the name for this... it is like a 5" piece of pipe)
45 degree with large (female) end towards engine
Homemade ABS Male Coupler (4" long piece of pipe)
22.5 degree
Longer 7" piece of ABS pipe (no picture)
Rubber Coupler
Assemble the pipe pieces in place to get the angles correct. This assembly is to test, measure and mark ONLY! A fitting that‘s glued crooked can throw off the whole run and/or won‘t fit properly with the next piece. Discover these problems during the dry fit rather than after the pipe is glued.
Assemble the pieces in the above order and then rotate the joints until a proper fit is achieved (make sure you leave room for the battery!). A proper fit should route the air DIRECTLY into the MAF housing without any changes in direction.
After you are satisfied that everything is in the right position during the test fit, get your Paint Marker (I used Silver) and mark each joint so that a line is drawn across the pipes where they join each other.
This picture shows what you are trying to achieve
Also mark where the Emissions Control hose will join the main 3" pipe so you can drill a hole there for the fitting.
Once everything is marked for proper fit, disassemble and remove the pieces, noting which go where... Prepare your glue and work with one piece at a time since the glue works very quickly. Due to the fumes I recommend gluing these pieces outdoors. To glue the pipe, push the joints together with a twisting motion to spread the glue. As you are twisting LINE UP THE MARKER LINES YOU MADE IN THE PREVIOUS STEP. Hold the joints together for a few seconds so they won‘t push apart while the fast-drying glue sets
After a minute or two of gluing you will have your intake assembled! If you marked the spot for the Emissions Control hose now is a good time to drill the hole for it. You want to drill the hole SMALLER than the fitting you are going to glue on since it sits on top of the pipe. I used a 1/2" drill and then hand filed and sanded the hole inside and out...

OPTIONAL STEP!
I chose to paint my intake with some Matte Finish Enamel to try and match the other underhood plastic pieces... it is matches very well now.

Clean your intake inside and out! Clean the INSIDE until it is CLEAN!!! Make sure you haven‘t left any plastic bits or plastic dust inside!!
Re-assemble the battery box and put the battery back... hook everything up and admire your work!!
Here I am installing my new Hella Micro DE lights and you can see where the
filter is located behind the bumper. I have not touched this filter since
install approximately 2500 miles ago.

Questions?info@ferraridoors.com