The Booster Speed Limiter is a module of the Boosting locomotion; it provides a particular functionality for its parent Booster. If it is disabled or removed, then the relevant boosting functionality will behave as by default. Most modules can optionally affect change globally (for both hands' Boosters). Booster modules can also depend upon conditions specified by their dependencies settings.
On this module you can tweak the speed limit past which boosting will not increase the player's speed.
You can also setup input to toggle speed limiting.