A buddy of mine had Invinca-Shield on both his '03 SVT Cobra and on his '03 Mach... very nice. You really can't see it at about 10 feet, and the protection is great.
There are several brands that use a similar (or exact) 3M protective film (it's actually from the aircraft industry and they use it in racing, too). Star Shield Armor is another brand, (
www.starshieldarmor.com) -- that's the brand that is factory optional on Lotus vehicles, which my buddy also had. He highly reccomends it on new vehicles... if you've already got chips, well, it's a toss-up.
It's a bit pricey, and you want to find a good installer, but it's much, much cheaper than re-painting.