fass or airdog?
 

which filter system would be a better buy fass or air dog? and does it improve milage and performance?

This was my main issue when it came to buying a lift pump... I ended up with the Air Dog. I love it. The FASS is more expensive and in my opinion your just paying for the name. The Air Dog and FASS are the same systems more or less. The FASS will run louder where as the Air Dog you cant hardley hear. Mileage will improve some, and as far as performance you will notice better throttle response out of the gate. The Lift Pump is one of those upgrades that you need to really build upon to notice the difference.