I have a base z with manual trany and sport package. From what I have read getting the JWT intake will give the car a nice growl. According to the description for the Nismo cat back exhaust will also increase the noise the car will make. I would like a good sounding car but don’t want to attract too much attention at the same time. How much louder will the car be with both?

It should stay reasonable with those two bolt-ons. I personally think the Nismo catback is a bit tame compared to some others. I don't think this setup will harbor too much unwanted attention.

Myself, I kinda want my car to sound like an F1 car!

Your car sounds like a Ferrari!