That is tforce old MPS6. He now has an Audi S4 seen below or in the link below
The Half Million Dollar Cruise
With regards to fuel economy, in the end yes I think I might help seeing that perhaps there's a small weight saving to be made and generally better exhaust gas flow through the less restrictive larger diameter 3" pipe and smooth bends. Will you be able to notice the difference in economy from stock...? Probably not. In fact you may be inclined to put your foot down more to get the benefits of said modification which, consequently results in worse economy. A modified intake will help with economy I reckon, the motor doesn't need to work so hard through that stock paper panel filter, think of it as a tiny straw. Ideally, intake, TIP, DP would all work together to assist in greater economy, still think its hardly noticeable to think about though
My 2 cents anyway