A Cumbrian man admitted driving dangerously when he appeared before High Bailiff Michael Moyle.
Thirty-six year-old Andrew Laidlow, of Appleby, was stopped by police at 11.30pm on May 23.
They had followed him in an unmarked police car fitted with a video camera as he reached speeds of up to 87mph.
The officers also saw him cross double white lines as he drove from Glen Vine to Ballacraine.
They stopped him and, when they showed him the video playback, he apologised.
Mr Moyle adjourned sentencing for reports, and bailed Laidlow until July 21.