Supertrapp - rings and stainless wool

I've heard mixed reviews about adding rings to a Supertrapp muffler. Note, I have a KTM LC4 640.

Does it increase power?
Is it louder?
Can you add more than 6?
Did you feel that you needed to re-jet the carb?

Also, Supertrapp's website says that you can replace inner dampening material with stainless wool to make it louder. Has anyone heard the difference?

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