Just wandering if you could change your 5th gear out and put a smaller one in for better mpg and top speed? Wouldnt want to change the pullys and loose torque.
British (and I presume Buellers in Europe) get bikes with different gearing. UK buellers often switch to US gearing. So technically changing the gearing must be possible, but if you already have the standard, I don't know about going w/ something custom.