I'm going to buy a Nissan 300zx an I was wondering what upgrades I should get like engine spoiler exhaust ect what do you guys have in mind

You will find that aftermarket parts are getting increasingly harder to find. I agree with Tom that the most important thing is to go through the car and drain, flush and fill all of your fluids before adding aftermarket parts. I would put at least 500-1000 miles on the car first. That way you will find out if it has any issues you were not aware of. When you are ready for aftermarket parts, I would start with a nice exhaust upgrade, for a better exhaust note. Wheels and tires are always a good upgrade. You can get a package from somewhere like tire rack. They will come to you already mounted and balanced. All you need to do is mount them on your car. I would not waste a lot of time on engine performance items, as your Z does not produce a lot of horsepower, especially compared to a 350 or 370. I still have my 1988 300zx (by the way I am selling it if anyone is interested), and I purchsed a 350z roadster about a year ago. The 350 has had some work done to it, and it makes the 88 seem underpowered.