I went on a group ride today and everything was fine. We stopped several times along the ride and my bike was running normally. At the end of the day my buddy was going fast 100 MPH or more out in the back straights so I follow and kept up. Well my bike was bogging in 6th gear past 8500 rpm. Once I hit 8500 or 9000 rpm the bike just didn't want to pull into the higher rpms. It would but it took a lot lot longer to get into the higher rpms than usual. As soon as I got back to the city I noticed that the bike also had a different sound to it from idle. It now had a sound similar to the rumble on a harley style bike. From a stop the bike would be sluggish up to about 4000 or 5000 rpm and then will magically jump into it's normal self and pull away. I took the bike past 10,000 in both 2nd and 3rd and it seems fine in the higher rpm's in those gears. I'm worried something is wrong with the bike and I need some advice. I also plan on taking it into the shop next week just in case because now the bike is scary to ride. I just put in a -1/+2 sprocket conversion with a new 520 DID chain. I took it on at least 2 or 3 rides since the install and there was no problems.