I have used K&N filters on all my vehicle for the past 15+ years but this is the first CAI system I've installed. It is very easy to install for anyone who does simple maintenance. You can notice the improved acceleration, it works. I am pleasantly surprised that it DOES increase the mileage in my Mazda 6 by a couple MPG. There is a strange 'growl' at low rpms but it shouldn't be so bad that you would want to 'unload it' as a read one reviewer say. Using the Sport mode of the transmission makes that go away. Very happy with the product.