First the 300ZX, and now the 350Z and 370Z can take advantage of the same proven BDE vibration isolator to replace the OE rubber mounts with direct replacement BDE Billet + Polyurethane mounts.
The BDE vibration isolator design is unique in that it 100% mechanically contains excessive engine movement with high-strength 6061-T6 aluminum construction and grade 10.9 hardware. By design, the Energy Suspension® polyurethane bushings are preloaded during assembly to ensure both upward and downward forces are controlled at all times and the polyurethane material is never placed in tension.
In contrast, stock engine mounts are preloaded only by the weight of the engine sitting upon them. Unfortunately this leaves an enormous window for upward movement which imparts a tensional force into the relatively weak rubber material and its bond to the mount's metal shell, effectively fatiguing the material and weakening it. Eventually the stock rubber will tear and the mount becomes useless at controlling engine movement.