Given the aerodynamics (or lack thereof) of the FZ6 coupled with the rev limiter that won't let you redline anyway, I'd be very impressed to see evidence of a 150 MPH or over run. I'm talking GPS or healed speedo, not indicated because it's also known that the speedo with a stock config is an easy 10% off throughout. So, 150 indicated means you're doing about 135 actual.
Given shreveport1's test on the center stand with 165 indicated and zero load, that is only 148 mph.
I am talking about stock bikes. Change the sprockets and this can be extended some. BUT, you will still hit the proverbial wall, that wall being wind resistance. There is a point where the FZ6 doesn't have the needed HP to push the bike any faster through the air. Somewhere on an old thread at the other site, someone proved a lot of this and video'd some of it.