Mr Guy, 31, was found dead in the driveway of his home on Aorangi Rd, south of Feilding, on July 8.
A post-mortem confirmed he died from several gunshot wounds.
Police have called several time for help identifying the drivers of two vehicles seen in the Aorangi Rd area on the morning of Mr Guy's death.
Detective Inspector Sue Schwalger said today police were disappointed with the lack of response.
"The more time that goes by without these drivers coming forward the more we have to consider the movements of these vehicles as suspicious," she said.
"Aorangi Rd is a rural road and there is very limited vehicle movement at that time of the morning.
"If the drivers of these vehicles were going about legitimate business we need them to come forward so that we can eliminate them from the inquiry."
No detailed descriptions of the cars were available, but both were seen driving along Aorangi Rd toward Campbell Rd, away from the location of Mr Guy's home, between 4.30am and 5am on the day of his death.
Police yesterday confirmed they had gathered CCTV footage of Mr Guy and his wife Kylee from local businesses to confirm their movements in the days before his death.
They would still like to hear from anyone with information about three chocolate labrador puppies that went missing in the hours before Mr Guy's death.
On the day of his murder, Mr Guy got up early as usual to go milking and drove his ute to the end of his driveway.
He stopped and walked around to the front of the ute, and it was then that he was shot and killed, police said.
