Get Flowmasters only if you're a redneck. Honestly, those mufflers are fucking shit. You're replacing OEM 409 stainless (possibly 304 polished stainless tips) with aluminized junk if you go through with this. I've yet to hear a single Flowmaster setup sound nice, and if you live in a state that uses salt for winter road conditions, don't expect longevity from the Flowmasters.
If you're serious about an exhaust system, get Magnaflow, Borla, or any other stainless setup. But all it will do is just increase drone and volume. I tried a set of Pypes on my 07 Mustang GT and went back to stock after 6 months. The drone was unbearable. The drone-free aftermarket systems (if they exist for your application) are usually 2-3 times more expensive due to money spent on NVH testing to reduce/mitigate the drone. Redneck engineering is less expensive, essentially slapping on a pair of Flowmasters and making a grin while permanently losing your hearing.
Here's my take on the Ford V10:
It is just a 5.4L V8 with 2 extra
cylinders. It cannot rev high enough to make more power and take
advantage of extra valves in the cylinder heads. It also guzzles gas
like crazy. While it is a V10, it is not the same as a Lamborghini or
Dodge Viper V10 engine and you won't get that sound of the Ford.