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For jetting, call Rick at Peak Powersports or High Roller customs. They both have 860's w/ turbo's that run strong. My stock bore I currently run 360 mains vs 480 stock w/out turbo. I believe one of the XP turbo's Silber was running an 880. He might be the best bet for your setup.
Right on thanks that gives me a pretty good idea of what to try first.