Well if it is the 1.8T you want then go for an Audi TT 225 lump (or the 210 out of an S3 or Leon) With the forged internals they are built for mega power (same pistons as G60 I have you know

). 300 bhp can be easily seen from this engine and 400 if you throw a bit more money at it.
Question is that is it really worth going for mega power in FWD. However there is an answer, buy a Rallye then its 4wd all the way