hacking speed limiter on August Tuesday e-bike?

I recently picked up an August Tuesday cruiser e-bike (lightly used, at 1/4 retail ) Solid, simple, heavy, with a basic cadence PAS that cuts out the assistance at about 23mph. The bike has a Bafang 350 w rear hub motor, simple mini combination control pad and charge meter, no visible controller, and much of the wiring is internal .

What do you suggest as ways to keep the boost at higher speeds? I've already addressed the front brake issue with a larger rotor and upgraded caliper, fitted a MB suspension fork, and a suspension seat post, and swapped out the (almost apehanger) bar for something a bit lower.

48V or 36V? Might not be a speed limiter, as 23 mph is pretty good for a 350W Bafang.

36v.

I hadn't thought of that possibility, but it *feels* like the assistance cuts out at about that road speed, independent of what gear I'm in (cadence) It sort of "hunts"...assist kicks in and out as speed drifts up or down around 23-25 mph.