Hey Nick & Ursula, I installed the AquaTunePlus on the ’99 Chrysler 300M, 3.5L. I had been getting around 27mpg, it varied between 26-27mpg. After installing your system, I immediately achieved the 25% increase in the mpg. After tweaking the air adjustment, I went to 37mpg. Just wanted to let you know that I am totally happy with the system. Thanks again for guiding me with the air adjustment. I really appreciate the great tech. support. Have a great day.