I am in the process of modifying an 05' WR stock exhaust and since a few guys are asking for photo's. Here's 4 pretty good photo's of the O5' exhaust to let you know what your dealing with. The 1st photo is just a lay out of the parts. The 2nd is a photo of the empty silencer shell looking from the mid pipe/header end. The 3rd is a photo of the mesh baffle without the packing, silencer shell and end cap removed as looking directly inside from the back of exhaust. 4th photo shows a close up of the mesh baffle so you can see the 8 welds (4 more on the other side) that hold the 2 different sections inside. To disassemble the silencer, you will need to drill out all 8 rivits where the mid pipe connects to the silencer. You do not need to drill the 2 rivits at the very end of exhaust unless you are planning on removing the plate that holds the spark arrester and exhaust tip in place. In my little experiment to start, I plan to drill these inter sections out to have a straight through flow and use a PMB insert w/spark arrester screen cone and see what happens. I don't have a stock YZ pipe to look at, but it seems like this set up may be very similar while retaining the stock 05' WR look which I prefer.