only trust shops that know there z's...not sure which one your talking about...yes get parts from coz or courtesy parts if coz doesnt have it....o2's are tricky but not impossible...sparkplugs are simple i wont go into that...but if you have a ratchet and sockets...you can do it all...for the o2's...the pass side you can get at when you take out the battery, and the drivers side you need to buy a o2 socket wrench...just search youll find it...as with alot of jobs...its easy with the right tools for the job...i will always do my own work on the z