Well, I can't help you out to much here....other than the mounts are much stronger/stiffer meaning the engine won't move as much under load. On the other hand, the Nismo mounts won't absorb vibrations like the stocks ones do.....
There are at least one other manufacturer of the motor mount kit, but they're very hard to obtain here in the states...and more $$$. I think there by URAS or something like that.
BTW where can you get them for $230??? most sell them for $275
