I run Holley so I’m not familiar with issues that can crop up with MS nor can I diagnose that thing over the Internet from 1000s of miles away but they need to be logging and if the dyno shop can’t log, diagnose and tune, why are they in business? They need to check for any type of configuration issues like a rev limiter Or spark cut safety or coil dwell/ignition setup errors. That graph isn’t even reflective of engine only power so hard to say what’s going on. You got anybody building and tuning big power stuff in your area? They’ll likely know how to diagnose.