Forget what I said, I have found some data. My honda runs 16/43 (272km/h) standard so I put on 16/44 for the island giving a top speed of 266 or something. Is you ZX6 a 2003? If it is are these the correct gear ratio figures? Primary 2.022 1st 2.923 2nd 2.056 3rd 1.772 4th 1.450 5th 1.272 6th 1.153 Final drive 15/40 If these are correct your 1st gear is lower than mine and the rest of the ratios are wider spaced. The best combination I can find is for you to run a 15-38. I don't think you'll rev it out down the front straight but it should be very good for the turns. The ZX6 gearbox above is close ratioed 1st to 5th the tall 6th for cruising. Good for the road but shit for the track.