So I followed s3dave's Injector cleaning guide and the throttle/engine response is now much smoother and I seem to have a much nicer idle. http://www.audi-sport.net/vb/a3-s3-f...pic-heavy.html
Thanks to s3dave for such a good guide.
In addition I also bought a refurb kit from Mr Injector uk which included new viton o-rings, filters & plastic washers.
It was pretty easy to remove the old filters by inserting a screw that caught the old basket and then allowed me to pull it out, the old washers I just broke off. (you can see the screw in the old basket next to the ladies bum in the picture - yeah I know I didn't realise until after I'd taken the photos that the old newspaper I was working on had an advert for ultrasonic lipo on the back)
Putting the washers back on was a bit tricky until I got a 8mm socket an used that to push them on squarely.
The filter baskets pressed back in using a vice.
The packet says to use a tiny amount of DOT4 brake fluid on the seals to ease reassembly - and christ does it make it easy to fit the injectors back in the fuel rail and manifold.