Take the top off the muffler casing. I did this with an electric die-grinder and a lot of cut-off wheels. I also used a metal blade and my sawzall. Don't forget to cut out all the spot welds on both of the chamber walls...top and bottom. There are three brackets that need to be cut off in order to take the top off in the first place. Save these and mark them so you remember where to weld them back on. You can see what I am talking about in step 9.

Then cut the the main pipe about 1/2 inch in from the housing. This isn't pictured here, but you can see it in step 6.

Once this is cut the guts will lift out, then it is time to hack everything apart. The goal being to have the rear chamber wall (the one facing you in this picture and marked with the arrow) disembodied from the rest. This is not easy, and takes a lot of time. I used a sawzall and die-grinder to accomplish the task. You need to remove the mini muffler and all pipes.