I just had my motor mount replaced because I was experiencing some grinding/vibrations during hard cornering. The bad motor mount caused my engine to shift enough during hard turns to upset the driveline geometry. Porsche updated the part for my 986 to a 987 part number, and I hope it lasts longer than the 58K my old mount lasted.
The grinding is gone, and another side benefit is that the vibration that I used to feel when letting off the gas pedal at around 3000 rpms is also totally gone. Here's a picture of my old mount. You can see that the rubber has totally ripped apart, and pieces of the rubber are missing. What a cruddy part.
