Thought this might be of some interest to others. I know its a repost, but the original post was inside another thread. So back in the day, when my S3 was a 1.8t and on the road !! I did a log with the standard airbox with a drop in k&n filter. The max g/s I could get was 198g/s with the crappy map that was on the car. I bought a very large filter (K&N rd-1460) for the stroker build and thought I would test it out on the K04 setup. Excuse the dirty engine and "awesome" plumbing elbow K N Universal Air Filter RD 1460 | eBay I did a log a few days later with the large filter and found that I had gained 16g/s just from fitting the filter, the power was noticeable and when the DV dumped the boost it sounded like a bus dumping boost - I had the biggest grin on my face for awhile but then it got embarrassing around town. Wouldnt mind the sound if I had 500hp I dont know if a filter will make everyones car a bit better, my guess it would probably come down to the mapping, but it does show how a filter can increase the airflow to the turbo.