What is the cheapest insurance for a 2008 Mustang?

I paid $ 157 on a 2000 Dodge Ram 1500th I recently bought a 2008 Mustang V6 Coupe, and my prices have increased dramatically. More than $ 600 dollars per month. I am currently insured by the farmers. I also have a 18-year-old son. What is car insurance is cheaper? So I would advise any other value in reducing auto insurance rates