US-based Willis, the 2006 Commonwealth 1500m champion and 2008 Olympic silver medallist over the same distance, lowered his personal best for the 3000m by 3.71 seconds, eclipsing his previous best time of 7:40.62 last July in Zagreb, Croatia.
The Wellington-born runner has had a long association with Wanganui, regularly supporting the annual Cooks Classic and acting as a mentor for young visiting athletes.
"The personal best mile and his first sub 3.50 mile last week in Oslo followed by that impressive New Zealand 3000m record was great to see," McNab said.
"Nick attended two Young Olympian Camps when still at school and he has returned as a mentor and has spoken to the group on many other occasions.
"The latest was during the Young Olympian Tour in Wellington this January."
The 31-year-old now returns to his base in Michigan to continue his preparations for Glasgow, where he will seek to win his third successive 1500m Commonwealth Games medal.