Welcome aboard, I have a 1999 1.9 and a 2.5 Z4 from 2003, you have arrived at the best Z Forum, loads of advice when needed and help from members near to you if needed. Bolster your toolbox with a scanner/code reader if you havn't already got one will save you lots when you have to use it to trace any faults that are bound to crop up. I use Laptop based software BMW INPA and BMW Scanner 1.4 and a handheld Creator 310+. All available on ebay or Amazon. Creator 310+ is circa £50, the laptop software with the cable and interface are a lot cheaper you only need an old laptop running Windows 7 or XP, maybe Windows 10. You will need a 20pin to 16pin OBD2 cable changer to use the laptop and the Creator 310+ to plug either in to the 20pin Diagnostic port in the engine bay. The 16pin OBD2 socket under the steering wheel can be used but it will only read the engine and gearbox modules. The 20pin in the engine bay will read all modules fitted to the car in particular the airbag system. The 20pin to 16pin cable changer is available on ebay for little money.