It's pretty typical to see around a 10% gain on most modern sport bikes by adding a full exhaust system and fuel controller, but most modern sport bikes also have ram air and the R3 does not. These tests were also all done with the stock snorkel in the airbox since that's how I have to race the bike in the supersport class at CVMA, so there's definitely a little more room to gain by removing the snorkel and possibly by changing the air filter once an aftermarket option is available.
And yeah, it's a lot of money for what seems like a small gain, but when you're racing, tenths of a second count, and a 10%, or even 6% horsepower advantage or disadvantage can be huge.
I'm very anxious to see how the exhausts from other manufacturers do, I'm planning another test as soon as I can to compare the Yoshi full system, a modified stock system with the catalytic converter removed, and I want to test the system that Spears Enterprises is developing. I don't expect too much difference between them, but we'll see.