I guess I should preface this by saying this: I am just brainstorming here.
Since my buddy god the extra super sweet deal on the 2002 A4 with a blown up engine I have been underneath one of these little beasties way too much. The rear suspension is very similar to the layout of the XR4Ti, which is not a bad thing.
My idea is to remove the Audi engine and transmission as well as front drive bits, modify the firewall to allow a little engine setback and replace lump with either a Ford 5.0L with a T5, a Lexus V8.
No real reason other than to build a RWD sedan to drive the kids to school in and drift on the weekends ;)
I don't know the answer, but your ideas are relevant to my interests, and i would like to subscribe to your newsletter.
I vote 5.7 litre Toyota V8. :)
Hey, that sounds like a great idea!
You'd lose your IRS with this idea, but what if you just took the entire drivetrain, including the rear, out of a Mustang GT (or 5.0 LX) or something? At least you wouldn't have to worry about the rear with that beast out back.
A4 motors aren't that expensive you know 
Anyway, I don't know how strong they are, but given how over-engineered the parts in most Audi's are (for example, the 016 5-speed is nearly the same strength from year to year and is used behind V8 Porsches and midengined Lambo Kits)
Worst case, they aren't hard to come by, but I've not heard of anyone having to change them out when performing psycho swaps, etc.
2002 3.2L V6 = 2500-4500. (and there is a car with bad engine available for almost Challenge money)
And remember the idea is lose the FWD portion of the OE drivetrain adding much more pressure on the rear diff.
I doubt that it would care.
Quattro info....
That link ought to help a little as it seems you'll need to swap to an older Torsen rear diff or sort out the electronics (Good luck!)
Stefan
