Well, I installed the FI exhaust yesterday. Installation went smooth no major issues. It took about 1 to 1.5 hours from start to finish. Compared to installing my headers, this was a walk in the park; no leaks, no SES light. The tips aren't perfectly center of the rear valence openings but no big deal and I have the infamous hiss now. The craftsmenship is top notch and the packaging of the parts was exceptional.
Anyway, the Z now sounds like it should. It sounds pretty much the same as on FI website: 370Z_ Header.wmv:
370Z_ Header.wmv - YouTube
I got a 'thumbs up' from my neighbor as I pulled the Z out of the garage
The exhaust thunders to life at start up then settles into a nice audible grumble. This exhaust is insane when you start dipping into the throttle. And WOT is just crazy insane.
Added bonus: POWER. The butt dyno is doing the happy dance
The headers /FI exhaust combo pushed my cousin and I back in the seats when I punched it in 2nd gear; haven't felt that feeling since my turbo chipped Audi. Thanks Tony and the FI crew.