I live near sea level. I put on the dyna with no carb mods and noticed an immediate degradation in mid-range performance and MPGs. Loud back fire when decelerating on the freeway.
I'm jetted up one stage now (147.5 main) with the white spacer at 1/2 thickness, performance and MPGs have noticeably improved. I still have soft backfire when changing gears.
One mistake that I made was not double checking my jet sizes before I ordered jets, now I need to re-order the #55 pilot.
I would suggest budgeting time to pull the carb, replace the "phillips" screws on the top and bottom of the carb, and do the spacer mod right away (prolly less than $5). Note the size of your stock pilot and main, and order 2-3 stages up for the main and 1 stage up for the pilot, as well as a replacement bowl gasket.
The closer I get to having this machine dialed in, the more I feel like I own the machine. But then I've only had the thing for 8 years.