Not much you can do in the way of tuning or making it go faster really, but could be worth investigating the state of your intake manifold flaps if they haven't been addressed before, and whether your ports are coated with carbon build up - a charming characteristic of FSI engines. Will be worth addressing from 70,000-80,000 miles and there are lots of threads on the forum about it. Just had mine all done and it's like the engine was being strangled compared to what it feels like to drive now.
Some common problems crop up every now and again. Water ingress due to blocked drain points, leaking washer fluid bottle, soft close motors packing up if you have them on your S8, that's about it.
Tinkering with the exhaust is a must though, it's so muted and restricted from factory. Even just tying the butterfly valves open on the back boxes improves things immediately. Removing a pair of the centre silencers improves things further (which I got done at a place I can highly recommend in Romford), and that's where I stopped with the exhaust as I wanted to keep the stock tailpipes and get a nice burble at low speed but full V10 symphony when my right foot is down. Other members have gone with full cat-back Milltek systems.