Wow. I was at about half tank, a little over 100 miles, and I took out my resonator and I took off the top of my air filter box. I kept driving, it was alot louder and I noticed a little more power. When I filled up today I had gotten an average of 28.5 miles to the gallon! Thats the most I have ever gotten. I'm looking forward to see what I get on my next tank. My 'rents have a 01 passat which gets like 26 to the gallon. I went from the least mpg in my family, to the most. I'm happy!