JBW, it's factory. You've probably seen a few A4 or even A3's sprayed up in this colour. It's called 'Hibiscus Red'.
To my knowledge, however, it's the only S3 in this colour. (one or two members might tell you otherwise, but until I see photographic evidence, I call BS! )
Looks tidy. I like the matching yellow Magic-Tree air freshener!
A cheap simple additional/mod would be to replace the orange front indicators with the chrome (orange glow) units. It just cleans the front end up and keeps it 'silver'. I've got pics from my old A3 with said addition if you require photos.
How about some A3 Turbo wheels too? eh, eh? I've got a set, again, from my old cars.. Yours for £30. (PM if interested)