I have one. But only rode it 60 miles so far since the jack frost is having making up for past mild winters.
The restriction isn't much, and its a cheap plug in to get rid of it. I have not had mine past 8,000 rpm yet so I can't say how it feels up top. i'm sure it will put a smile on your face. The throttle response everywhere between idle and 8k is great. The bike is smooth as silk. Great street bike and even better race bike.
I have not raced mine. But a partner of mine does race an 08. He had an 07 that he crashed at MidOH. The 07 has cams/headwork/pistons blah blah blah. Plus Ohlins shock/forks. He crashed that 180hp 07 and the next session went 2 sec/lap quicker on his 08 with stock suspension. Power mods on the 08 were a slip on, zbomb, and bazzaz fueling. Nothing special.
02 919 (RIP)