I have nothing to do with the Insurance Industry, but I can at least offer what the insurance cost me when I was 26/27 and bought my '02 V6 Camaro.
I was paying $1100 a year for full coverage (higher levels than base). But I also have the cheapest insurance company in the state of NJ (though NJ is one of the highest overall to insure a car).
It sounds like you plan to have the car insured under your parents name to save money on insurance? I don't know how it works in your state, but in NJ you can't insure a vehicle that isn't in your name. So your parents would have to take the loan out in their name, not yours. Do you live with your parents? If so you'll have to be at least listed on their policy as a licensed driver that lives in the household. That would raise your parents insurance overall price also because there is the potential for you to drive one of their cars.
My parents made me get my own insurance when I got my license/car just for this reason.
I'm curious to hear what the price difference has generally been between insuring the V6 vs V8 since I've never really asked about it.
(All of this can be ignored if your insurance rules are totally different than NJ's.)