You can use a dremel but it may take awhile. Just measure a ton and use a tapeline to keep you going straight.
Is this the factory exhaust?
2001 #62. Ohlins rear/valves, Micron high mount, HyperPro damper, SharkSkinz, Tyga billet triple clamp, Tyga Carbon Fiber fender and hugger, Ti bolt/custom subframe/alien motion 8 cell diet, 15/41 520, COP conv. PCIII, Venhill lines, modified air box, turn signals in headlights...<deep breath> ZG Touring windscreen, Tech G rear sets, CRF450 rear master w/HRC cover, Tokico 6 pots w/V-pads, CRG Bar end mirrors, PSR Shorty levers-use only clutch, wanna-be basic racer paint, Roman Gold PC wheels