Induction changes come with a number of risks of varying factors and I decided to experiment with some theories to gain the advantages with a minimum of pitfalls....the only compromise being that I may not gain as much as a full blown induction kit.

UPDATE: look at our Induction Testing here

 After looking at the descriptions of induction theory in that they are designed to get more air to the intake avoiding the factory kit which is designed to reduce noise and to pull in cool air.

Hear the fantastic sound, unless you have a subwoofer and good speakers don't bother! ;o)
-TTC + Milltek Exhaust - Windows media 3.7mb

UPDATE:- Here's a couple more using a different sound system, its more realistic sound.
ttsoundbite1.wmv  ttsoundbite2.wmv

I modified the factory box to pull in air from the lowest and frontal positions, it would be advise-able to adopt a cold air feed
into the installation if possible


1. Airflow Less restrictive
2. Deep note Induction Rumble
3. Dump Valve PSSSHHT sound ;o)
4. Probably very minor temperature improvement over a cone filter,
standard cool-air scoop is retained so some cool air is still being pulled in.
5. Stealth - virtually factory fit look.
6.Option to stick with standard paper filter or cotton filter
7. The above option means some sense of security over MAF failure
8. Better protection from moisture.

Possible Disadvantages:

1. not as good an improvement over a cone filter but a Panel filter may solve that.
2. Different induction tone
3. Engine heat may collect in traffic.


We did some induction testing on a standard car, click here for the tests and found that:-
The P-FLOW was the best for induction flow, but noisy
The VTDA was the best compromise between flow/sound
The Wakbox mod the best for sound, stealthy, flow gains and value

Fitting is easy, you'll need a Flat blade or jubilee driver and Philips screwdriver, A 10mm spanner and 10mm long socket:-

1. Remove the 3 bolts of the battery cover

2. unclip the AMM connector
3. Undo the Turbo Hose jubilee clip.

4. Undo the 2 Air filter cover screws on the rear side of the box,
remove the top filter cover, sliding the turbo hose off as you lift it and then withdraw the air filter element.
. Remove the 2 10mm bolts holding the base down

6.You should be able to remove the base of the Air box completely now, wiggle towards the engine and then up.
Lift from the turbo hose end and pull away from the intake hose that's bolted to the wing.

7. Take the base of the box and cut panels out as shown, there is no need to cut out panels everywhere, the volume of air will always be restricted by the diameter of the Air Mass Meter induction pipe which is a lot less than these cut outs will allow through.

All the versions below are simply different ways of cutting the same holes,
I found a hole cutter and angle grinder the easiest way of making a professional job. Noise levels are the same with all versions

Just stick to the front panel and two lower panels I have been doing.


Mk4 - A little production line going

Avoid cutting any more holes over this as a balance between increased airflow and air temps is achieved.

8. Refit the Panel Air filter, (below you can see the restrictive OEM pipe.)

9. Refit all the components,  go out and enjoy.

The Low speed pickup is accompanied with a deep note burble, letting off the gas comes with a PSSHT sound, Hard acceleration is no more noisy and the increased airflow seems to give the car a slightly more torque-y feel.

Just added this Cold Air improvement to help keep cold air flowing into the airbox.


The Ducting in the pictures below wasn't very good, I purchased

SFD69-1 69mm ducting

from www.sfsperformance.co.uk

which is so much better

Some Drainage pipes from Homebase and ducting from Halfords 

Heated and moulded to a different shape

Installed a scoop and feed to a ducted area

Ducting fed into OEM pipe, after this picture was taken
the pipe was then pushed out to form a perfect impression inside the OEM pipe.

The ducting attached to both pipe pieces

Installed in the car to pick up the air forced up from the lower grill.

Overall I think this is helping the low end pick up a lot, initial standing start lag is there but it feels like a few extra horses come on tap just after the colder air has begun to push in.

Update 2

I have taken a cutter to my car and updated my cold air feed to be a single run of pipe.

I had the OEM snorkel cut short to allow room for the VTDA but behind it is connected a hose
The plan is to go straight down and forwards to the front lower grill

There is no room at all to get a feed down and out so I cut part of the inner wing away, many dremmel discs were used along with a couple of angle grinders and the rough edges painted, glued and covered with edging

This would allow the pipe to drop straight down without effecting the arch liner.

A single screw is used to attach the front of the angled scoop to the bumper

A small hole is drilled into the elbow to allow any water ingested to escape
Some  airflow will obviously go down the hole but should also force heavier water out the hole instead of up the pipe.

I'm very pleased with the end result, I reused the oem clip hole for the Alien pipe,
The arch liner went on as smooth as it came off.

The scoop is nice and stealth

On the road the recovery times of the airbox temps are down from 2 minutes to about 30 seconds
The VTDA was running around 4-6 degrees above ambient temps before,
now it is running around 1-4 degrees above ambient temps.
The Wakbox mod is running at ambient temps with this cold air feed.