I am also a bit skeptical.
That's a big gain from just a catback. I know Ford has to deal with pretty restrictive sound level legislation, but it just seems unlikely that would have left that
much on the table, unless they were trying to save the 6.2 from humiliation!
But if these are accurate, what an awesome upgrade! Don't see pricing for that kit, but it looks like the standard F150 exhausts are about $350 and the 4" Super Duty's about $100 more, so likely under $500 for this system. Honestly, even if it's half
the reported gain it is still a decent upgrade! Great power bump with little downside. And IMHO far less likely to cause any warranty issues down the road than ecu tuning.
They also have a sound clip
on their web site.
Here are the above dyno charts saved as jpeg's...