In order to remove the exhaust the only thing at the EXUP that will stop you are the cables attached to the pulley so theoretically you could remove the cover then the 2 bolts holding the cable guide which would then give you enough slack on the cables to allow you to remove them with the valve mechanism still in place. Having said that you really should be regularly servicing the EXUP to prevent issues further down the line and this would be a good opportunity for you to take the assembly apart, clean and lubricate the parts, and replace the bolts with stainless items if they are still the OEM parts. As ever Pats guide is the place to be looking - http://www.cartestsoftware.com/fz1/exupmaintenance.html
There is also a recent thread on removing the headers which might be of help for you - http://foc-u.co.uk/index.php/topic,23736.0.html
There is also a recent thread on removing the headers which might be of help for you - http://foc-u.co.uk/index.php/topic,23736.0.html