We added to the rear sprocket because MXA said to, and we're all sheep. Baaah. Don't confuse top end hit to top speed. I still use my 09 spare rear wheel and I liked the 49t. I've got 2 races on mine now and I like the instant throttle response. For as much as I will be spending on my 2010 Yamaha , I hope the transmission isn't a problem. Mine will be here sometime next month. I don't plan on getting a pipe for a 7100 dollar bike!!!! My wife never says anything until this year when she heard Ron say "Retail of 8K"!! I got the look!! That's more than we paid for her leftover CBR600RR last year!! She said "How much will it be worth next year?" I said "About 3K just like this year." She said no pipe after that. Hey Doug, BTW does yours start now that you have some time on it? I had the same problem on my 09 last year, but after a couple of hours , the problem disappeared.