spiderserie4 you did the right move ! I won't try to say that my electric power-steering setup is an easy DIY project for everyone. At the beginning of my project I had the opportunity to buy a cheap S4 for parts. I thought first about using P/S parts of the S4 and fit it on my S3 but it's not an easy project either. After that I thought about using the S4 as base for my project. The S4's body was about in the same shape than the S3's body. I really like the front look of S4 but I prefer the rear look of S3, at least in black. I know that people usually don't like the hard plastic rear spoiler of S3 but even if it sounds strange I like it very much in black. That's a kind of coming out : I like S3's rear spoiler
That's one of the reasons why I've chosen to paint my project car in black (it was white originally). On my Silver S3 the black spoiler contrasts too much for my taste but it's not too bad.
Back to topic... it took me a lot of time to think and to fit my EPS system but as everything else if I had to do that again it would take a lot less time. The good thing about my setup is that everything is hidden. That gives me a cleaner engine bay look (without hydraulic hoses, etc) and nothing is apparent inside either. I hope the feeling will be great on the road though. I can adjust the steering assistance and many rally racers use that same setup in UK, I assume that the road feeling will be good. I will let you know as soon as I can test it... but not really soon in fact !!! Maybe next Summer.. or the next...