I take it that you do not have your Z yet?
When you find the "one", go over it and make sure all the basics (fuel,air & fire) are working properly. A stock, well tuned Z is still pretty impressive!
If you want more, start with the low hanging fruit (horsepower). There is a good bit of additional performance to be had for a relatively small amount of dollars.
My '90 was bone stock. All I have done performance wise is a Haibeck "chip", Corsa exhaust, and modified air intake. The difference is noticeable and I can put it back to bone stock in less than a couple of hours.
It has more power than I can reasonably use on a daily basis. More is always better in my mind, but weighing dollars to usability I am good. (For now!)
You can go to gear changes, headers, porting, etc., but I would recommend the "easy" stuff first and see where you are.
My opinion and worth exactly what it cost !!!!!
