Excellent write up guys! It made installing my door speakers really easy. However, if you have a '13 Premium, you will need the front door speaker spacers from a '11 or '12 Mustang. The '13 has a modular component set up which can't be used with aftermarket speakers. The Ford part nbrs for the spacers are;
4R3Z18B947AA - Right Side Door
4R3Z18B947BA - Left Side (Driver) Door
Less than $30 shipped From Tousley Ford.
Also, check out Crutchfield for the Infinity Reference speakers 6832cf. Very competitive pricing, free shipping and free speaker wire adapter (correct polarity). Good luck!