Since sorting my recent S3 issues, I decided to try the 'Wak Box' mod that I stumbled across whilst looking into solutions. Drilled the holes as per post. Mass Air Flow rose by around 4g/s, which was a result!
However, I found the noise to be really disagreeable and irritating. At low revs, there is a loud booming resonant noise, particularly at very low revs under load (circa 1500 in second after turning into a road from a junction). It smoothes out and is less 'booming' as the revs rise, but still pretty intrusive.
Being induction noise, it simply sounds unpleasantly 'flat' to me (and somewhat reminiscent of a 17 year old lad's 'pimped' Citroen Saxo), unlike the sweet and crisp sound of the Milltek at high revs
So, after 48 hours of the wak box, I covered all the holes and plumbed in a 100mm wide hose I had lying around, from the airbox to down near the front at the side of the battery (pretty much as Tuffty did in his superb build thread)
I get the exact same airflow as the Wak box mod (around 4g/s more than standard airbox) without any additional noise over a standard airbox. Result
Took 45 minutes in total.
I understand that some might think more noise equates to more power (as an engineer I can tell you this is not necessarily true) and some may even like that flat, booming, induction noise, but for those that prefer low noise with the same airflow I recommend the 100mm pipe approach.