Buying guide?

[OCDetails]

So I'm looking at s5's for mid year change I have a a4 b7 atm as my first car and well now I've had it almost 2 years come august I want a change. I love the v8 noise but with the s4 and rs4 they have that problem with timing chain rattle and some other engine problem that's common. Does the s5 suffer with the same problem with the v8 ? I'm guessing it's the same engine but maybe they have solved those 2 common problems?

Also so has anyone revo stage 1 there s5 on here? What sort of fuel mpg did you gain or loose?