Sorry to revive an old thread, however I too experienced a knocking noise upon acceleration and changing between 2nd and 3rd gear. Last week, I floored it at a roundabout and I heard what I can only describe as a gunshot in the car. I had obviously broken something pretty catastrophic. One of the rear diff mounts had completely sheered off. The reason for this... One of the two bolts that hold the diff in place had corroded and snapped, this was the knocking I was hearing. Had to replace the whole diff (brand new they're £4,000 + labour). Car was out of warranty by two months. Fronted the bill. I love my stinger but after this, it's gone!