Something you need to know from both my own experience and the experience of members on the TDI forum.
1. Does not produce any increase in power as measured on a dyno on turbocharged engines. (K&N type of filters in general)
2. From engine oil sample testing, the filter does allow way too much dirt past filter media, and it shows as high silica readings. This was my personal experience 15 years ago with a K&N on an '87 NA 4.0L Jeep Cherokee and about a year ago findings of TDI forum members with same problem that's cured when OEM filter is replaced.
3. No one reported any useful increase in MPG.
4. At $50 or more for one of these K&N filter and the only gain being the filter is reusable, it would take 7 or 8 years to pay for itself. But the problem is the likelyhood of engine damage occurring.
If you still think these are the best thing since popcorn, just remember these were first designed for race cars to protect the engines from large particale injestion. We all know that race car engines don't get driven for years before being rebuilt. Most are rebuilt in under 1000 miles. The K&N filters were not designed to protect your everyday family car from the fine dirt and dust particales that the street car is exposed to for years and tens of thousands of miles. They sell these things to street users for the simple reason there is big proffit involved and more sold more proffit.
