I'm just pointing out the fact that when you remove things that are designed for emissions laws (both gasses and sound), then things are going to change. You can always repack your muffler if you want, but there are a lot of people on the forum here that, from what I have read, gripe when things aren't the way they expected (My favorite does have to be one I saw several months ago about "why isn't my brake lever on my left handlebar?"). I understand a lot of guys have never had a bike before, but I do expect people to use the thing on top of their neck, mostly their brain. I understand for the younger people out there (and I'm only 28), that they expect to be able to look on the internet for everything and have a well informed idea of what things are going to be like. Real world things are different.
And loud with minimal gains is I guess what you're referring to. I'd say close to 10% gains in hp numbers is a GIANT gain from an exhaust. When you're starting with 9hp, nothing will be a big gain until you break it down into percentage. A 1hp gain from 9 to 10 is just over 11%. If I had a 10% gain from my Leo Vince slip-on with my Aprilia, I would be pushing 172hp at the rear wheel. Instead, I got only about 2-3%.