All of my pukka competition bikes (2T enduro's) has this kind of fitting for the headers and most didn't leak gas or even seep oil. It was also a just a bit easier to get the pipes off for the very frequent ring changes.
I don't see that it should be a problem.
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"The final measure of any rider's skill is the inverse ratio of his preferred Traveling Speed to the number of bad scars on his body." Song of the sausage creature
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