UpRev Osiris is the proper method for tuning 370Zs and to be honest it's the only way...this is way better than a canned tune. You can either buy the software and do it yourself or go to an
authorized tuner from the list on the UpRev site. IMO it's better to just find a reputable shop and pay for the license and tune, I paid $500 for the license and few hours on the dyno tuning my car. If you just buy the software from UpRev it starts at $500 and you won't get the best possible tune compared to being on a dyno.