When you are working with twenty-six (26) horsepower, you really need to minimize any loss of power. In the case of the R50, the bike was louder than it should be with the new mufflers. It turns out that it was losing exhaust right where the exhaust headers met the cylinders. I had a pair of gaskets, but did not have the exhaust collar tool. 
This is maddening, because you really can’t use another tool without defacing the collar. I have seen a few of these where someone took a hammer and chisel to the collar and created an ugly mess and an unusable collar. I ordered a tool and patiently waited to tackle the job. The gaskets were thin, and the collar on one side was not on all the way. No wonder it was a little loud. Armed with the right tool, it took five minutes to tighten things up and get back some of the missing 26 ponies….