Undo the two bolts on each side's connection clamp. Undo the one bolt on each side holding the stock muffler to the battery box. Undo the hose clamp bolt up underneath on the cross-over pipe.How do you take off the muffler without taking off the head pipes? Drop the battery?
You might be able to wiggle them enough to drop them from there. If not, you've likely GOT to drop the header pipes.