This is the handlebar LCD and Control Box positioned under the rear rack.
The LCD has 5 speeds plus rider pre-set cruise control and battery power indicator.
To go from 350w PAS to 450w Moped disconnect the white "speed limit adjuster", fill in "Single Vehicle Approval" form, using the moped  EEC chassis number on the bike. 
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/973873/motorcycle-single-vehicle-approval-application-form.pdf 
Be covered if you get stopped, house insurance, if applicable  -- your Bike/Moped.