Street or race bike?
On a street bike, I wouldn't worry with it. The pipes come out the very bottom and aftermarket pipes don't look much different. I know we know the difference, but I mean you could park your bike in front of the store now, then park it in front of the store with the Termi's, and nobody walking out of the store will be able to tell a difference.
Nobody needs an additional few HP on a street bike that already makes 180-190hp. Hell my Grom is a great street bike and it only makes 11hp.
If you have the money burning a hole in your pocket and need to spend it, then go for it. But personally, on a street bike, I wouldn't bother.
If this is a race bike, different story.