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Just when you think you've seen it all...........
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<blockquote data-quote="Dangerous Dave" data-source="post: 381781" data-attributes="member: 1299"><p>:blink: :blink: </p><p></p><p>Maybe you should ask Yamaha that question. In their '80s 2-strokes they called it YPVS (Yamaha Power Valve System). In their '90s 4-strokes they called it EXUP (Exhaust Ultimate Power Valve). They still use it. After Yamaha's patent ran out, pretty much everybody jumped on that bandwagon. Similar idea, different purpose in life. Yamaha has always used it to optimize torque characteristics, not sound characteristics. The Yamaha servos have always been well before the silencer, but nevertheless, they've survived decades inside exhaust systems.</p><p></p><p></p><p></p><p>I remember those, but the "Y" completely diverted the exhaust gases outside the exhaust system. This uses different passages within the muffler itself. One way is straight through like most aftermarket exhausts, the other is through a more complex baffle system for more noise suppression. Pretty darn clever.</p></blockquote><p></p>
[QUOTE="Dangerous Dave, post: 381781, member: 1299"] :blink: :blink: Maybe you should ask Yamaha that question. In their '80s 2-strokes they called it YPVS (Yamaha Power Valve System). In their '90s 4-strokes they called it EXUP (Exhaust Ultimate Power Valve). They still use it. After Yamaha's patent ran out, pretty much everybody jumped on that bandwagon. Similar idea, different purpose in life. Yamaha has always used it to optimize torque characteristics, not sound characteristics. The Yamaha servos have always been well before the silencer, but nevertheless, they've survived decades inside exhaust systems. I remember those, but the "Y" completely diverted the exhaust gases outside the exhaust system. This uses different passages within the muffler itself. One way is straight through like most aftermarket exhausts, the other is through a more complex baffle system for more noise suppression. Pretty darn clever. [/QUOTE]
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Just when you think you've seen it all...........
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