Yea they all have the same basic layout but the difference is being platform specific. You go to a Nissan tuner because they know how to tune your motor, and have done it countless times. Bringing your car to someone who knows little about tuning infinitis is not a wise decision IMO. Yea they might do a good job but your taking a bigger risk than someone who tunes VQ motors for a living. And there is nothing wrong Ilya with doing UpRev through a “mail in”. If you want hundreds of testaments from people that have done it gone on G35 driver.