I've taken mine of numerous times. Get underneath the pipes and use a screwdriver to open the gap between the front heat shield and the truck stack, squirt in WD-40. Move to the back of the bike, grip the stacks and begin wiggling them back and forth while pulling hard as you can, be sure to put a foot against the tire so the bike doesn't just roll back. You'll have them off in no time.
I went to Home Depot and bought some copper pipe and couplings and added enough length to extend the piggies outside on the stacks. She is quiet as a whisper now.

FYI, Grumpy's tips make no difference to the volume, they only improve the look.