The speed limit near Westmere School, which a nearby resident described an "endless parade of boy racers", will be dropped to 70km/h.
But neither council nor residents expect it to combat the problem.
Rachel Stewart took concerns about the intersection of Francis and Rapanui Rds to Whanganui District Council in March saying it was a hotspot for boy racer behaviour.
She had concerns about noise but also safety, particularly given the school was there.
Councillors ordered an assessment of the safety of the intersection which has a 100km/h speed limit.
That found no crashes had been recorded within 50m of the intersection over the past five years but council's senior roading engineer Rui Leitao recommended reducing the speed limit to 70km/h, which council's infrastructure committee endorsed on Tuesday.
A survey earlier this year showed cars travel near the intersection at under 85km/h 85 per cent of the time but there were vehicles clocked going much faster, including one over 150km/h on Francis Rd.
Leitao told councillors he didn't think the speed reduction alone would stop burnouts but also said there was little "engineering" council could do.
The intersection was designated "over-dimension" truck route which meant there needed to be a wide turning space.
But councillor Murray Cleveland, whose view on speed reduction was "negative to say the least", suggested some sort of engineering, such as closing the boundary of the school from the road or installing a barrier which trucks could mount but would stop boy racers should be considered.
Leitao said a mountable barrier would be expensive, estimating about $300,000, and did not think such measures were required.
Stewart said the reducing the speed alone would not stop boy racer behavior.
"If you want to stop the problem there is a suite of things," she said. "And you're looking at some of them and I really appreciate it.
"But the overall issue is you have so much space on that corner... for them to just go round and round, five times, six times, then drift down the road sideways - and they're doing it.
"I still think there's room for some psychological barrier or physical barrier where trucks can still turn."
There had been crashes on the intersection despite the official data recording none, she said.
"I know about them because they end up in the ditch across the road and then they call their mates and get towed away without the cops coming because they've been drinking or they've done a burnout before they've crashed.
"I'm not sitting here lying to you. This is what I see because I live there."
Cleveland said; "We've got engineering example on parts of the heavy transport route which show something can be done."
Leitao argued trucks needed a big turning space which would always leave excess space for cars.
"It's quite a difficult thing to do. You could put little low lying barriers in certain places but still, they're very, large."
Councillor Charlie Anderson said it was a slow stretch of road anyway and backed the reduction.
"By making it legal at 70km, at least it's going to be enforceable for the boy racers wanting to go through at 90km or 100km. We've got to start somewhere."
Councillors also voted to automate the electronic variable speed sign outside the school and drop the speed to 50km/h during school drop off and pick up.