You're asking "How high is up?" You don't give your location, driving record, grades, car year...everything AN AGENT will ask you when you call. However, at your age and with a large, expensive vehicle, expect some hideous figures, especially if you have to carry comp and collision coverages. Between those and fuel for a 4.7 liter engine, you'll need to be independently wealthy.
You might want to start off a little less "grand", with, say, a used Civic or Corolla; they may not be babe magnets like the GC, but you'll be able to afford them. When I was an agent, I used to call business like yours vacation money.
Whatever you do get, try to stay on your parents' policy if you can; you should get the multi-car discount and have the clout of their existing coverage.