I have used the musket repairs but not on PE's There is a few guys on the PE forum who have used them though and i know one guy was very happy as the musket repair was made from a lot thicker metal. They should be set up and welded on the bike to get them in the right position though. I usally find lots of tiny cracks in pipe around the spring loops. if you end up using the one you got give it a full burn out inside. Its makes them really clean, lighter and shows up any more cracks or holes in them.
Also with the mufflers, they will be all clogged up with oil and the packing will be usless and the bike will be loud. Get the muffler cut open, take out the perforated core and clean it, re-pack with new packing and weld it back up again. Its can all be done neatly to look like it has been worked on.