A new over-track pedestrian bridge and improved viewing areas are also a feature of the work done.
Driver-turned-chairman of the V8 Supercars commission, Mark Skaife, has had a big hand in the design and thinks it will be a winner.
"Some of those races I had with Greg Murphy here were great and something to always remember," said Skaife.
"We're excited to be coming back to Pukekohe and we don't want to lose that great Pukekohe character.
"But at the same time we needed to configure the circuit, thinking about the future and the safety factor.
"I'm very happy with what we've done with the back straight and the new couple of corners - we've made it as good as we can."
The foremost reason for the new section is safety.
"There was not enough run-off at the end of the back straight at the hairpin to satisfy safety requirements and it coudn't be fixed using the existing track lay out."
The new section, from a racing point of view, will create a couple of good corners that will enhance the racing quality and provide more passing opportunities.
The cars will be approaching the new turn five at 225km/h with about 100m of braking allowing for passing.
Between turn five and turn six the track is 14m wide with an offset of 80m between the corners.
The way the corners have been configured allows a driver to dive down the inside, but will hurt the run out of turn six and through the kink down to the hairpin, so strategic thinking will be very important.
The cars will still get to about 185km/h after the new set--up before they have to use the anchors and haul the car sharp right for the 65km/h hairpin - giving another passing opportunity.
In effect the new layout now provides three places to pass, which will mean more entertainment for the fans.
All the kerbs have been modernised and parts of the track resurfaced. Widening has been undertaken at turn one where drivers re-join the track after exiting the pits and barrier alignment is more energy-absorbent in the faster sections.
The characteristics of the older sections of the track haven't changed much and the fast, flowing and bumpy nature of the track remains.
Defending V8 Supercars champion Jamie Whincup is the only driver to have been able to get a good look at the new layout at close on race speed, albeit in last season's car.
"I had to get something coming out here and doing a bit of promotion and 20-odd laps gives me a bit of jump on the others, even though it's not in my racecar," said Whincup.
"I think the track is fantastic. It brings back some memories and it's still got that character it had back in the day. Certainly the new stuff has spiced it up and it's a lot safer for all the drivers.
"I had a ball out there and I can't wait to get out there for qualifying.
"Heading into the new turn five will open up some passing opportunities for sure.
"You can pass down the inside if you're game under brakes and then you've still got the hairpin for another opportunity," said Whincup.
