The Te Tapui Scenic Reserve includes the two peaks of Te Tapui at 492m and Maungakawa at 495m. The Te Tapui Loop Track to the summit of Maungakawa starts at Piakonui Rd, west of Matamata, northeast of Cambridge and southeast of Morrinsville. It can be walked in a clockwise or anticlockwise direction, although the DoC description recommends the anticlockwise direction.
However, the times and distances on the DoC site do not entirely agree with my experience. The distance is close to 6.5km measured by GPS instead of 4km, and the time of 3 hours should be ample even with a long break at the summit.