The hiss is normal (if it is when you lift your foot off the throttle).
Full CBE you have plenty of choices, Tanabe, Fast Intentions, Berk, etc. Honestly it comes down to what you like per your sound.
Check these two threads out:
370Z Exhaust Sound Clip data base
the370z.com's Exhaust Quick Reference Guide
Where are you in Texas? Check the Texas section, can always meet up with people and hear different combinations in person which will help.