UFO lack of power

[Kerry Griffith <kgriffit@parkcity.k12.ut.us>]

Guys,
What's wrong? My 91q has never felt strong in the brake department- my wife's 89 80q has much better braking, as does the extended family A6. I've got new (>5k miles) rear pads & rotors, and newish (>10k miles) "friction rings" in front. The fronts were replaced under warranty because of UFO wobble, but the dealer declared the pads OK. I really have to stand on them to decerate rapidly, and they're virtually non-existent for a few scary seconds when they're wet. I don't have typical dead "bomb" symptoms, but something isn't right: I simply don't have powerful braking. Please tell me what my mechanic needs to check. TIA

Kerry