Few things replaced in my z; 2 front speakers, thermostatic v/v (stuck) and A/C tensioner (making abnormal sound).
Also had a small problem in the gearbox, repaired by GM warranty. That’s all… mine still stock not even air filter

 

I have that, sounds like valve lash to me. i hate to think of having remove all that crap to adjust lash. i swear it's just from the driver side, but not sure.

only other prob so far is lighter socket needs to be replaced. shorts out whenever i plug in my cell hone charger. just a PITA really. otherwise, it's great and only 40k.!