The Brise starter works fine while the battery is fully charged, however when the battery drops to around 12 volts the cranking speed drops and makes the engine difficult to start.
After talking to Rich at RLM he suggested changing to a 24v starter circuit and wiring in an additional battery. The new battery is wired in series after the output from the start solenoid before the starter motor. As I had a spare battery I decided to give it a go and mounted the battery in the passenger footwell.
The engine now cranks faster than ever and starts a lot more consistently. I am currently still using the Brise starter but I may swap back to the standard hayabusa starter at a later date.