So school me. Leased 2013 A4 - 2.0T w/ 8speed auto tranny. Putting the tranny in S mode with the stability control Off/Sport mode already transforms the vehicle. Looking to do an upgrade for performance but also to help MPG. My highway mpg in 8th gear I am very satisfied w/. But to sell the idea to my GF, savings in gas or increased MPG would make it a possibility. I don't want to go anything exchaust related. I posted a thread about an intake for a little extra performance and MPG, but the more I read, the more I see that the right software flash really does wonders for these 2.0T's performance wise. I hear it's like a whole different vehicle. Two main issues is.... does it help gas mileage? And is it detectable when going in for a service? Car is leased for 42 months so I guess I would have to reflash the stock ecm before turning it in, or maybe not even have to bother...? School a newb 
