idle and after i shift....at first i found my smoking problem and it was my PCV valve hoses...when i did my rebuild i didn't change the hoses and put new ones in... i also didn't know that the Z has restrictors in the PCV valve hoses...so i ordered a new PCV valve hose kit from Z1, pulled the plenum, and installed the new hoses....sure enough in one of my old PCV valve hoses the restrictor got kicked sideways and it was causing oil to blow by....i had no smoke for a good few months and now its back. Id hate to tell you to pull your plenum just to check your hoses but if everything else checks out ok, there is a possibility it is your PCV valve hoses...any easy way to see if its your PCV valve hoses is to pull your air balance tube off and look inside your intake for oil. if that's all good then i would just start checking other areas like you could pull your throttle body hoses off to see if there's any oil residue in there, or pull your downpipes too and see if there's any oil in your turbos or your downpipes....
like i said im chasing the same problem so if i happen to trace mine ill post something for you! but im starting to lean more towards rings on my engine because the compression isn't quite up to par! Good luck!