I was considering going down this route but decided to go with an ED30 just for ease of modding and keeping a VW warranty.
There is a guy on the Audi forums whos running 380BHP+ on an S3 with a re-map, Downpipe and sports cat and Cat-back exhaust, apart from the IC the S3 and ED30 motor is the same..
Having the higest power MK5 in the UK is quite a different thing to having the fastest

Seems a good offer but I would imagine there would be lots of conditions, dates they will need the car to be available at shows, mag pieces etc..
Jonny