500 mains are stock, I have run 480's safely for a season, am currently running 490's. You don't necessarily have to rejet with a silencer, but you want to check your plugs and wash. Contact the manufacturer of the silencer for any info. I ran an MBRP silencer for a season, and they recomended no jetting changes.
__________________ "It's such a fine line between clever and stupid"</span>