So I just had the EA Stage-1 tune done for my 2017 S5. Very significant difference. Overtaking is even more quick and effortless than it was in at S5 level. During a full-on acceleration my heart almost bursts from the excitement.

It's also nice that when I'm cruising gently in "efficiency" mode, and then put my foot down to negotiate a roundabout, it thumps forward quicker, without the very noticeable delay that occurs in S5 mode.

I should have done this upgrade years ago.