Why do oversized PV covers do what they do?

[motogroove]

Whenever I am faced with questions of subtle adjustments or modifications like this, I like to remove the subtle part and think in extremes.

If the PV chamber was tiny, let's say the size of a thimble, it would not break up these bad resonance waves or add significantly to immitating a longer pipe. So, the engineers need to go bigger than a thimble.

If the PV chamber was really big, let's say a gallon, it would immitate a pipe that was way too long (even for such low revs), and probably be way beyond the size needed to disturb the bad wave impulses. And of course it would be bulky, heavy, and more exposed to damage.

There's an optimal size range anyway.

Also note that our factory cover has cooling fins and the aftermarket units don't have room for that. Maybe that's the trade-off right there - a little extra cooling. Think about that little region of the head, pumping hot exhaust gasses more than any other region of the head. It's hot there.

I'm not good enough to work my 300 hard enough to be taxing the thermodynamic limits of the machine. But that doesn't mean that cooling isn't important for a top rider (who probably gets along fine with, maybe even enjoys a less linear power delivery).