The front crossover pipe overlaps the header pipe by about an inch on each side, and I'm quite sure the pipe will be difficult to remove, I had to cut a slot on each side, and bend the pipe to get it loose from the header .
The first time you do this job, it can be a real pain, but once you get it apart, and apply anti seize to the areas, it's nowhere near the job the second time .
If you do cut across the threads, use a small file to 'dress-up' the threads, and then use the new exhaust nut to chase the threads, or if you have a thread file, use it instead .