I picked up my 370 a year ago on April 1 (no joke, really....). And to celebrate the occasion, I installed a Nismo "H"-pipe and resonator (kept the stock muffler) over the weekend. It turns out to be a nice set up. There isn't an excessively loud exhaust tone, and there is improved throttle response and a little more low and mid-range grunt. Nice and stealthy.
It's still not as fast as my TT was/will be again, but since that one is down for an engine rebuild, the 370 is the fastest Z I'm driving at the moment.
Aside from the inevitable April Fool's Day jokes we will all be subjected to, I just wanted to share this milestone.
Enjoy your day, and your Z's.
Dave