Let me give you the facts less the opinions from company that does this every day. Every intake system K&N produces is tested for performance increase on multiple vehicles, Each of these vehicle is 100% stock. This does not been there is nothing to gain from changing the exhaust or adding a programmer.

The truth of the matter is that when you reduce the restriction on the intake side and allow the engine to breath more efficiently the net result is horsepower. Your MPG increase will vary because there are many factors that contribute to the overall outcome such as the how far off the factory program is, tire press, driving conditions, driving style, ect. Ultimately your mileage increase will depend on how inefficient your engine is running to begin with.



The first steps to getting your engine more efficient is to increase the intake efficiency then most people decrease the back pressure in their exhaust by installing a cat back system. These are typical done first to because when you get more air in you want to get more air out, Then you may want to consider putting programmer on. The reason I say this is because you want to make sure your fuel delivery is matched to your air flow. If you do it the other way around it hard to say what you’re going to get.

Again with a K&N system you will get a performance increase on a stock vehicle, your mileage is hard to say since there isn't a repeatble test platform. But more often then not you will see an increase. I personally picked up 1mpg.

What year is your excursion?

If you have further questions feel free to contact my customer support team 1800-858-3333 or send me a PM.