3M used to be crap film. It would yellow easy and didnt self heal like the better stuff. But I think I heard they bought venture shields out and took their tech. They used to be the best. Now there is another company making good film called Xpel. Their film is similar to venture shields. You can use a heat gun and heal scratches and swirls. You can also wax and buff it.
But always remember you should NOT ever put clear film on headlights. Especially HIDs. It will hold the heat to the lens and eventually the lens will craze or crack.
My advice from doing clear bras for years, is to do the whole hood and whole fenders. Rocks will bounce and skip across the hood. You might not get damage on the bra, but they will still damage the hood past where the bra ends. Most precut kits only cover the first two feet of the hood and fenders back. If you really care about the car, have those pieces made custom and get the mirrors, rockers and a few feet of the top of the roof from the windshield back covered.