Amuse just released their Extra STTI and RS-Silent STTI models for the Nismo 370z dual system. These will bolt up directly with the Nismo dual outlet midpipe.
There are 2 tip designs to choose from as you'll see from the pictures. The "Extra" picture is an example of a single wall tip, while the "RS-Silent" picture is an example of the new dual wall tip. The tips are also 5mm larger than the previous models (120mm)
Another option that Amuse has always offered is a choice of tip burn styles. See the picture below for the different versions.
A Tail = Just the edge burned
B Tail = The full tip burned
C Tail = No burn; just the polished ti tip (not shown in the picture)
Check them out:
More info here:
Extra
RS-Silent
R1 Front Pipe
-Mike Bratcher