I've been thinking about a new lip for quite a while, and I simply can't figure out why it has not been made.
I was thinking about a lip for our car that is similar to the Amuse Superleggera 380rs:
The only thing that comes remotely close is a front lip that Seibon makes, called the GT lip:
What I've been thinking of is...What if you molded the Seibon GT lip pictured above to a regular 370z Nismo bumper. It would look something similar to the 380rs. You would have to remove the bottom portion of the bumper first.
It would also be sort of similar to the 350z Nismo front. (I believe thats the bumper that Amuse modified to make the Superleggera 380rs front, not sure.)