The head of one of New Zealand's largest drug syndicates has been jailed for 17 years and three months while his right-hand man received a sentence of one year less.

Feng Chih "Daniel'' Hsu and Aenoy Bouavong pleaded guilty to methamphetamine possession and supply charges.

The pair were the main targets in Operation Acacia, a 10-month covert police investigation into an underworld network spanning Auckland, Waikato and the Coromandel.

Police bugged telephones and intercepted text messages to crack the case.

The court heard how members of the group spoke in codes and used different cell phone numbers in their attempts to avoid detection by the police.

In sentencing, Justice Kit Toogood described the group as "a sophisticated, structured large scale operation'' that manufactured, sold and distributed the Class A drug.

Hsu was sentenced in the High Court at Auckland today to 17 years and three months in prison with a minimum non-parole period of eight years.

His second-in-charge, Aenoy Bouavong received a sentence of 16 years and three months with a minimum non-parole period of eight years.

But Hsu's legal problems did not end today.

APNZ understands the police are now seeking money from the sale of Hsu's BMW X5, money from the sale of his house and $985,000 in cash.

The application, under the Proceeds of Crimes Act, is now before the High Court and will be the subject of a future hearing.

Crown prosecutor David Johnstone told the court that Hsu was "the mastermind.''

Hsu's lawyer Ron Mansfield said his client got involved in drugs after his business failed but was relieved when police finally caught up with him.

"It does seem that he found himself in a lifestyle difficult to get out of.''

However, Justice Toogood said Hsu's offending involved over $5 million worth of methamphetamine which was motivated by greed.

He described Hsu as being "at the top of the distribution pyramid''.

When armed police raided Hsu's North Shore home in July 2010, detectives found 5kg of methamphetamine, 2kg of flu drug ContacNT - which contains pseudoephedrine, the main ingredient in P - a cache of guns and more than $20,000.

The discovery was described as one of the most significant seizures of P made in New Zealand.

Referred to as "elder brother'' or "Big Daniel'', Hsu was the head of the organised crime enterprise and was able to source large amounts of methamphetamine and pseudoephedrine from overseas.

The drugs were then distributed by Aenoy Bouavong to lieutenants.

Justice Toogood told Bouavong: "You were in charge of getting drugs onto the street where I have no doubt it caused great harm.''

Other members of the group who carried out courier and middle-men roles were also sentenced for their part in the methamphetamine operation.

Henry Anthony Mika was sentenced to nine years and four months in prison.

His lawyer, David Niven, said Mika received only $2000 for his part in the group.

"There was not a lot to show for it and it is a shame that message doesn't get out there more often,'' Justice Toogood said.

Thi Hong Lan Nguyen was sentenced to 12 years. Her lawyer Mina Wharepouri said Nguyen was further down the chain than the others and she had her own addiction to methamphetamine which she had since sought help for.

He said part of the reason the 28-year-old got involved in the group was to provide for her five children.

Justice Toogood described her as "instrumental'' in getting the drugs onto the street.

Another dealer and partner of Nguyen was Aenoy Keophila. He was sentenced to 12 years and six months.

Ka Kit Poon was sentenced to nine years in prison. Phokham Bouavong - brother to Aenoy - was sentenced to six years; and Tavita Maleko five years.

OPERATION ACACIA

* 5.5kg of methamphetamine.

*2kg of ContacNT.

*21 guns.

*$400,000 cash seized.

*22 arrests in Auckland, Waikato and Coromandel.

- Additional reporting New Zealand Herald

- APNZ