I run either 14/48 or 15/48 on my XTR..

Standard 15/45 is 4000rpm at 100kph 3.0:1
15/48 = 250 revs more at 100kph "4250 rpm" 3.2:1
14/48 = 500 revs more at 100kph "4500 rpm" 3.4:1

I have a 16 tooth I haven't used.. to put it back to standard ratio..
16/48 = 3.0:1 same as 15/45

14/48 is a good ratio for offroad... able to go very slow though river crossing
& gnarly single track etc.. Ok on the road..

15/48 is good if theres alot of seal to cover to/from the offroad rideing..

my feeling is the XT's are over geared for anything but road use..

Another couple of bonus is it puts the motor just above the 4000rpm
bad vibration zone & those extra revs help with the snatchy fueling issue
at low speed in traffic..

__________________
Harley Davidson..
The easyest way to turn gasoline into noise with out the side efect of horse power...