It just takes a throttle stop in the correct place on the throttle body to achieve the desired effect.
When I bought mine in 2018, it was fitted with a 25 kW restrictor to comply with Irish legislation for new riders, rather than the 35 kW which is A2.
It was dog slow and I couldn't figure out what was wrong with it until it came to me in a blinding flash. "Surely it's not fitted with a restrictor and all the previous owners haven't noticed...?"
A few minutes removing the tank and finding the miniature hacksaw and it was gone.
Thanks. I need to comply with A2 for my 22yr old to use - just needs a 'tificate I think so you can show it if necessary. Throttle limiter probably the answer - it was for his older brother on a Versys 650.