Yes, I would also like to know. I also just bought one, a 1989, and was thinking of going there yet this year some time. I have the same pipes/silencers.
It seems to me that they can't be all THAT strict about the sound there. They may not be fully enforcing the sound laws. I was up there with my truck the last weekend of June and there seemed to be some pretty louds quads there. Trucks too, for that matter.
Kevin