The pair were jailed for life, with minimum terms of 15 years. Arnopp pleaded guilty to murder partway through a trial in 2008, while Gilling was found guilty of murder at a retrial after a jury could not reach a decision after the first hearing.
Gilling's parole report said he now accepted he played a "significant part in the assault on the young man who died". Gilling was 17 at the time.
Waipouri was 39 when Arnopp and Gilling killed him in his flat on Rangitīkei St, Palmerston North, in a likely homophobic attack.
The young killers were found by police still at the grisly, blood-stained scene.
Waipouri suffered head, neck and chest injuries, having been beaten for more than an hour.
The tip of his penis was missing, an ear was mutilated and there were bite marks on his nipples, but in court the question of cannibalism was never answered.
Gilling met with the board over videoconference from Rimutaka Prison, in Upper Hutt, where he works as a baker at the staff training college.
"Mr Gilling had a very difficult childhood... As a result he has really had minimal expectations about life and the way forward," his Parole Board report stated.
In prison he has completed a rehabilitative programme, although he was said to fear change and could make anti-social comments if something went wrong.
"He is assessed as being high risk of violence, particularly if he has an unstructured life, uses substances and is in bad company."
Gilling was about to move to a self-care unit and the Parole Board said it hoped he would have guided releases into the community, including shopping, so he can familiarise himself with life outside prison.
The board also said Gilling should do his best to obtain further education in prison.
"Having talked with him, we think Mr Gilling is an intelligent young man and we hope that that can be brought out."
Arnopp's report said he was mostly behaving well in prison, although he initially had many instances of misconduct. Before killing Waipouri, Arnopp had offended regularly.
"Since that time he does seem to have turned his life around somewhat and it is appropriate to record that the last aggressive misconduct was back in 2016."
Arnopp had also completed a rehabilitative programme, but was still assessed as being at a high risk of violent offending.
After a transfer to Whanganui Prison in June, he had completed a drug treatment programme and was doing one on one counselling.
The board said it hoped Arnopp could have guided releases into the community and obtain release to work employment.
Arnopp and Gilling will have further hearings before the board later this year.
-RNZ
