Yeah, that white dust indicates a failed cat, BTDTx2. If anyone needs a passenger side cat, I have a virtually new one purchased from Euro-Car Service with approx. 2k miles on it, will sell for $250+shipping. It's for a '91 200q, but will work on an S-car, BTDT as well. Differences in front of the resonator really are only in the hangers. Taka