The box section was cut to size, I used inch and a half. The holes were a nightmare to get right because the captive nuts were sitting at differing angles meaning that the holes drilled for the bolts had to be done at an angle.
If you do this mod remember that one of the bolts sits right above the fuel tank so make sure its not too long.....!
Undid the seat cover and threshed the head rest out as well.......this means you can move the seat back even further.......
I am six 2 and it has made the world of difference.