Good luck with your new car. You don't have to get an extended warranty now. You can get one down the road before the factory warranty runs out. I drove my GT-500 out of the dealership last week and didn't take an extended warranty on it yet.
If you plan on keeping it stock then get it. But if you plan to mod it, don't because FORD will probably void it if they see mods assuming that is why the car has a problem.
Do not consider any warranty other than Ford. A Ford dealership will honor a Ford warranty but may not honor another. You might have to pay for repairs yourself and hope the other company will reimburse you.