Sean: did you manage to sort the engine in the A4? Dont think i ever saw an update on ASN after the timing belt went?

Do you think the M90 box will be up to handling 450hp?

The other option might be to use a T5, with some sort of bellhousing adaptor on it. I'm currently in the planning stages of an adaptor to mate a RV8 bellhousing to an Audi V8, and i'm sure T5's with RV8 housings are reasonably easy to come across?