Original post by: Robbie ,
Well I can tell you I had a FASS on my old Classic, I was very happy with it. The Fass improved throttle response and the smoke in the exhaust, I can't say exactly how much it improved fuel mileage though. The install was easy enough. I think the most important thing is always keep extra filters on hand, especially the water separator, they can be difficult to find when you may need them. They need to be changed or cleaned regularly and can affect performance if you do not. It is a good product in my opinion.