BOUND_4_HELL you said "The High Speed needle is set to Max RPM and backed out 100 RPM." Once you have the new muffler, and if the burbling is still noticeable, you might want to set the engine at max rpm and not back out the hs needle for the rpm drop. I switched to 50:1 on my second DL50 today and retuned the engine. There was a noticeable decrease in the burbling with the hs needle set at max rpm. No problem with vertical uplines either, well almost done...the 17lb WH Edge just kept climbing and climbing until it was a dot. It flat spun for what seemed like forever coming back down. Let us know if you do reset the max rpm and what the results were for you.

Chuck