Been riding liter bikes for so long I don't know what a 600 should be capable of. Handling is great but it just doesn't seem to make the top end HP the mags claim I should expect. Granted the mags probably get hand-built, perfectly-tuned examples, but their claim of around 160 top speed makes mine look wimpy by comparison. So here's the deal, stock '04 with a K&N filter and my rather non-aerodynamic ass hanging out will post 146 on the GPS. Speedo is indicating 157. When it was set up with a full pipe and PCIII and one down on the front, It would show 176 on the speedo but I did not have a GPS at that time and the sprocket probably threw in a 7-9MPH error. Anyone have a '04 or '05 GSXR that they have topped out? I know this is a track forum and top speed doesn't come into play very often but I figure if it's 10MPH off at the top, it's probably not performing to it's potential everywhere else. Go ahead and hurt me with tales of 160 MPH top speeds.
I don't know about your bike specifically, but more often than not the K&N air filters hurt the performance more than they offer gains. I wrote an article on the issue several years back, it's tailoired towards the RC51, but much of the info rings true across the board http://www.rc51.org/airfilt.htm The speedo on most Japanese bikes are very optimistic. With stock gearing they read about 7-8% faster than actual speed when traveling at roughly 70-80mph. That error is not static & grows as the speeds increase so by the time you indicate 130mph your speedo error can be as high as 12-14%. If you change your gearing to lower than stock (less teeth on the countershaft sprocket and/or more teeth on the rear sprocket) then your overall % of error is even greater. Lastly, you have to take into consideration how large of a rider you are, your riding position & even your gear. Larger riders or bulky gear that catches alot of wind causes major drag at high speeds. Even just popping your head up over the windscreen at 150+mph will result in an instant & noticable drop in speeds.
Yeah, that all sounds spot on. My FZ1 speedo really goes haywire at the big end speeds. The old front wheel, cable drive units seem more consistently (in)accurate than the electronic gizmos. I bought the bike with the K&N already installed or it would still have the stock element. Lost faith in K&N from a performance standpoint a long time ago. Thanks for the input. Shhhhhh, I can still go into SquidMode and claim I saw 175 on the speedo when I am talking to the unknowing.