I have looked at the site that cool! Go karts that run tuned pipes had what they called slipper pipes, they have been outlawed at most tracks from what I've read. The slipper pipes work and if it gets sticky, its cleaning time if you want to mess with them.
Andy I see nothing wrong with one of these pipes as long as you keep them quiet in the public as most people don't like noisy things and we got to keep up our image. Law abiding citizens that we are?!
Those type of pipes you have on the link might not be that loud my black bike's pipe is modeled on that pipes design, I don't have the slipper stuff inside but have the out side can and one stinger pointing at the ground for less noise. That is the first time I've seen a spring loaded pipe interesting and neat.
Good find.
Norman

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