Here are all 4 as a comparo. The pics are not the best but I did measure all of them for comparison sake. I guess the R1 is not much different than stock Ninja 250R. Where the cable ends lie is a tad different so there will be a little more circumference to make the R1 tube still a little bigger than stock. Not by much mind you but I did notice a slight change. Thus the reason on my earlier posts from way back shows a difference in the pics. I noticed more when I used the R1 on my Hayabusa but slightly different animal altogether. I don't have the stock Hayabusa to compare right now. After doing all the measurements and obviously seeing the difference, the R6 would be the best bang for the buck assuming you have plenty of adjustments on the cables.
Here are some more pics as well as the diameter measurements.
750 Turbo - 31.50mm
Ninja 250R - 36.75mm
Yamaha R1 - 36.80mm
Yamaha R6 - 40.75mm
