For the last few months we have been playing with intakes on both the K03 and K04 Golf GTi's. We first built a prototype of our own but we were dissapointed with the noise, its was all swooshing and wooshing, as if a hoover was fitted under the bonnet, but lacked that induction roar that most cars gain with a nice intake.
Another issue was the amount of noise at low throttle and low RPM, and lack of noise higher up the revs. This made 'everyday' driving a bit annoying if you wanted a subtle and quiet car t drive.
Our prototype was shelfed in favour of a panel filter, but performance dropped as expected. This was replaced shortly after with a Forge Twintake, kit fitted fantasticly well, performed well and sounded OK but was by no means quiet. We expected the enclosed filters to help, but they didnt.
Next up was a Dbilas, which is built extremely well and up to the usual Dbilas build quality that we expected but once fitted we did notice the car was far less eager to pull at low RPM, the dyno also confirmed this with a loss of 20bhp over the Forge item! Once we investigated where the power had 'gone' it was clear it was the tiny airbox with a smaller filter than fitted to most petrol lawnmowers!
But the plus point was that the wooshing 'henry hoover' noises were gone. So off came the airbox to be replaced with an open cone (universal item we keep in stock) and road testing was impressive, no swooshing noises and lots of eagerness that we had lost with the airbox fitted. The dyno confirmed this as did the datalogs and power was 4bhp higher than with the twintake fitted. The setup sounded fantastic on the road, perfromed well on the road and dyno and logs look better than both the twintake and dbilas kits individually.
The conclusion is that if you want a quiet intake, its not the type of filter as in enclosed vs open, its the material that the intake tubing is manufactured from. The Forge item is made from very thin aluminium, the Dbilas is rather thick cast alloy. The thickness of the tubing dampens the noise of the rushing air. I think the ideal solution would be for a manufacturer to bring out an inlet which has all of the benefits of the Forge kit but with the a heavier gauge intake tubing, this will give the power gains, the quality and the silly swooshing noises will be eliminated. Or just buy the Dbilas kit and a universal filter :)
