Op asked about what he should do with his spark plugs before getting the Z tuned. He should follow the advice of Moncef. Why ask us. We are nothing more then a bunch of dumb country bumpkins with no knowledge.
This is from Admintuning's website.
"Please change your oil and your spark plugs before getting your car tuned. For the VQ35DE engines we recommend the NGK 3672 spark plug. For the HR, VHR, and VR38 engines we suggest the OEM GTR spark plug. For the VR30DDTT engines, please contact your Infiniti dealer for spark plugs.
For NA cars, please set the gap to 0.030”. For turbo, supercharged and nitrous cars, a gap of 0.020” is recommended.
We do not recommend using Bosch injectors on the VHR but they will work fine for the HR and DE."