New safety measures will be introduced at the first major event in the motorsport calendar since three people were killed at the Jim Clark rally in the Borders last month.
The event, which takes place in the Dumfries area, forms part of the Scottish and British rally championships.
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Sandy Murray, of Police Scotland, was was giving evidence at the trial of a bus driver who denies killing Ryan Baird by dangerous driving.
34-year-old Christopher Peck was involved in a head-on crash with a drunk driver. His funeral has taken place in his hometown, Workington.
The arrests come weeks after a much-publicised series of appeals to mark the 30th anniversary of the 18-year-old's death.