So, I couldn't find any write ups on doing this, so I figured I'd tackle it and post it up for anyone interested.
Before I start, just fyi, this was done on a used first generation RS-5 I bought from someone on here, so I THINK it'll be just the same as the second generation can, but I can't promise that. Also, the typical "do this at your own risk, warranty goes bye bye, etc" applies. With that out of the way, here we go!
I'm not going to post up anything about tearing the can apart or putting it back together because that's covered by Yoshi on their website under "repacking". Go check it out.
So, first thing I did was mount the can on my bike stock so I could decide how much I wanted to take out. I have heard people do about 2 inches, but my main reason for cutting this was to make my Tripage IT as visible as possible, so I measured to where the LED's and diffuser start, which turns out where I need to cut about 3" out of it.
As you can see, the can is right at 12" long stock, so we'll be down to about 9" when all is said and done.
Next, I removed the can from the bike and got ready to work. You will need the following tools to accomplish this job; a dead blow hammer, a regular hammer, drill, drill lube of some sort (I used Boelube, but whatever you have should work), 3/16" drill bit, die grinder with a cutoff wheel, an 1/8" center punch, a rivet puller, safety glasses, and I recommend some gloves because these rivets get HOT.
Punch out the rivet stems and drill off the heads per Yoshi instructions. Remove end cap and end of can, again per their instruction. Next, drill off rivets at forward end of can (where the midpipe comes in) the same way and remove inside piece and attached baffle tube. Discard old packing (unless you want to reuse it, but to me this is the perfect time for a repack) being careful not to cut yourself on the wire mesh wrapped around the tube.
Now, measure in from the aft end of the tube and mark at whatever length you decided to cut off in the first step, 3" for me.
Cut along that line with your cutoff wheel, being careful not to let the cutoff wheel get away from you and tear up the wire mesh. Take your time, cut slow, and cut straight.
Here you can see about how much shorter the guts are now than they were/the can still is.
Next mark the outer sleeve at the same place, making sure to cut the forward end of it (otherwise you'll cut into the name plate obviously).