My question as well. The idea that the OEM mounts were going bad after 6 months is hard to believe. The ones in the race car are 3 years old and are checked often. The ones in the street Z are even older and they're fine.
How the mounts are at idle or at 3000 rpm aren't a concern, I'd like to know what it's like going up to 7000 rpm, down to 3000 and back to 7000 in a matter of seconds at WOT.