Most people are not brave enough to stand up to boy racers.
But Geoff Wilson is not among them.
Fed-up up with speedsters on his street, the Belfast man set up a speed camera system in his back yard to nab them.
Residents have long suffered speeding and noisy acceleration in the street, with some drivers going more than double the 50km/h speed limit.
But 57-year-old Mr Wilson’s ingenuity has resulted in seven convictions for excessive speeding – with two more boy racers pinged by his camera currently before the courts.
Police have tested and calibrated his system against their own car radars. They say his footage can be used as evidence in court.
The system works by measuring the time it takes for a car to travel 7m along the road beside Mr Wilson’s house.
When boy racer cars are heard accelerating up the road, Mr Wilson or his neighbours note down the registration plate.
A long-time driving instructor, Mr Wilson made headlines about four years ago after successfully disputing a speeding ticket in court.
He argued he was wrongfully pulled over by police after they recorded a car driving at 114km/h in North Canterbury.
Using his GPS as evidence, Mr Wilson convinced the judge that the real speeder was behind him on the road.
Mr Wilson said it was not uncommon for people to drive down his street at more than 100km/h.
He went to the city council some years ago to see if speed bumps could be installed, but nothing had been done, he said.
"I thought right, I’ll do it myself,’ he said.
The camera system has been in place for about a year, and it appeared the message was starting to get through, Mr Wilson said.
"The street has quietened down now. They (the local boy racers) know I’m serious," he said.
Some could be heard slowing down in front of his house, then speeding up again.
"The gutless ones go past and pull the fingers," Mr Wilson said.
But his stand has not come without a personal cost.
Not only did the system cost him in time and money, but he has also faced retribution from those convicted through his system.
He has had a rock thrown through his son’s rear car window, a letterbox thrown into his garage, threats from boy racers’ parents – in one case requiring an anti-harassment order, and bottles thrown at his vehicles and house.
But Mr Wilson said someone had to "take a stand."
"I’m out to get the guys going 80, 90 and 100 km/h. The speed limit is 50km/h, not 90km over the speed limit.
"I only do it if it is serious."
Mr Wilson said he did not have a grudge against car enthusiasts; rather his motivation was about "safety in the community".
"I love fast cars, too, but I know what to do and I don’t abuse it," he said.
"I know how long it takes for a car to stop. If a child is killed there because of a speeding car and I didn’t do anything about it, I couldn’t forgive myself."
He said his two sons were also car enthusiasts, but were not boy racers.
"The whole boy racer idea is strange behaviour," he said.
"This is about the male brain not perceiving risk until 24 years old. And yet we give them the keys to drive a lethal weapon."
Senior Constable Pete Carrington said any member of the public could set up a system like Mr Wilson’s.
"If you’ve got a camera covering an area which is measured and a computer system that works to a 100th of a second and you’ve got a clock on it, there is nothing to stop anybody," he said.
"It’s basic fourth form maths. Distance divided by time," he said.
"The fact he’s doing this and it works and it’s proven and the defendants accept it – that’s it."