One of the most popular [numerous] "Warbird" category aircraft in New Zealand are the North American Harvard 3* of which five were at the airshow to perform.
In the overall scheme of things, perhaps the Harvards are not the most exciting aircraft to watch, but their pilots do tend to put on a solid performance which most people seem to enjoy. For more information on these aircraft, check out the excellent New Zealand Warbirds website.
The aircraft themselves have a very strong link to New Zealand, as the Harvard was used as the Royal New Zealand Air Force [RNZAF] trainer in to the 1970's. Many of these aircraft are ex-RNZAF aircraft.