have you heard of sound performance? they got some pretty insane cars. i havent been there myself, but i have a few friends that take their cars there.
or isnt there a place called AMS? or something like that. not sure if either place is specialized in 370z...
Sound Performance
http://http://www.spracingonline.com/services/
ams
http://http://www.amsperformance.com/
i got no experience with either one,but there dosent seem to be much around us.