If you havn't picked up the latest issue of Performance Auto & Sound Magazine you should. The cover story is on a 2004 A4 1.8t Quattro. It's pushing 425hp(500hp with NOS). He replaced the turbo with a gt3076r. It's got 530cc injectors and many other goodies. It's pretty sick. There is also an article on a modified S4 pushing 600hp and 650ft-lbs. THe intire issue of the magazine is almost completly Euro tunners with alot about audi and VW. I suggest you get one and read up.