From what I have been told, it is loud when you get on it and quite when cruising around. Corsa’s Xtreme set up on the Gen 1 was the same way. Hands down, that is the best sounding exhaust I have heard for the Gen 2.
It's ridiculously loud when you get on it and pretty raspy. I haven't ridden in one, but I have heard it at events and I can only imagine the highway drone. Reminds me of the diesels that are setup to have super loud whistling all the time. If you want the truck to be as loud as possible it is the setup to go with and the guy who had it on his truck loved it so to each their own.
As for warranty tunes are discussed on every car forum out there and the answer is always the same and that's don't expect the drivetrain warranty to apply when you start altering the computers. Everyone is like "maybe, you never know" yet Roush etc offer their own warranties for a reason...