Finished stocks dropped 3 points to 52.6 and deliveries slipped 0.4 of a point to 53.9.
"While the recent rebound has been in all the right places, it's new orders that have stood out head and shoulders," BNZ senior economist Craig Ebert said in his report.
"This is a good sign that production, whose index strengthened to 60.4 in March, will sustain its strong momentum."
Manufacturing's fortunes are typically linked to construction with building booms providing demand for materials.
New Zealand has one of its biggest building pipelines in history with a major push to bridge the supply gap in Auckland's housing picking up the slack after the Canterbury earthquake rebuild passed its peak.
Across the regions, Canterbury posted the highest reading at 65.1, followed by the Northern and Central regions at 50.5 and 59 respectively and Otago at a more modest expansionary reading of 51.8.