only heard from word of mouth is that they can cause some problems.
heard cos it tightens the engine up so much there is no flex at all from the front of the car.
i dont know if its true and any bad effects, so dont quote me on it, someone should be along shortly to give a better answer anyway.
 
money better spent towards decent suspension, unless you plan on cornering hard quite a lot, there's no point, just needless added weight IMO.
 
strut brace doesnt really affect the engine whatsoever it helps turning in sharper and helps prevent front end of the car twisting, basically keeping the chassis as straight as possible. unless youre tracking the car every week its not really worth it.
 
I've got one on my GTi 8v which I use on the track. Been advised that a rear one can make the back a bit twitchy.
Incidently the later Audi S3 has a front one fitted as standard by Audi at the factory.
 
we put one on our vRS after it was lowered and it has seemed to improve the handling