Hopefully this may clear things up a bit:
R1 Extra STTi
This exhaust exercises the latest of Amuse/Nippon Steel ingenuity; STTi (Super Tough Titanium Option) and shaves off 19lbs. over stock.
RS-Silent STTi
As you can see this exhaust is focused more on flow and sound control. It is still one of the lighter exhausts available and stills provides power gains.
Super Silent Sports Catalytic Converter Set
This set includes a front pipe and two high flow cats for better flow and emissions control.
Different Gradation Options
Powerhouse Amuse - R1000 Full Titanium Race Exhaust
Amuse R1 Front Pipe
-Hunter