Review on K&N Cold Air Intake Kit: Boost Horsepower with High Performance Guarantee: Legal in All 50 States: Fits 1999-2005 BMW 3 Series (325Ci, 325i, 325xi, 323Ci, 323i, 328Ci, 328) 2.5/2.8L L6, Part No. 57-1002 by Black Miller

I bought this in June and wanted to wait a bit to actually test it. 6 months with it and I'm satisfied! It makes a nice raspy growl when revving past 3000 rpm. No annoying whine like the gaudy cheap CAI systems on the market. Fuel consumption, I can't honestly say, has changed. I've gone from about 17.9mpg to 18.1mpg in the time I've had it, but I also drive it fairly aggressively and in very bad traffic. The car definitely has better acceleration but is noticeably different from what it was before it was turned on. Installation was relatively easy, if you've ever worked on an e46 under the hood you can always check it out on YouTube ;)