"I still think South Africa are our greatest rivals," Hewitt said, "but when it comes down to it the All Blacks are clearly showing every team that in the last 10 to 15 minutes they go into a different zone - that's the difference."
Hewitt believes the All Blacks should win by at least 20 points.
Fellow 1996 All Black Matthew Cooper said matches against New Zealand's traditional rival may have lost their shine in what is now a congested test schedule.
"The British and Irish Lions are a great example of less is best - there's that real fever of anticipation and excitement when they come to your country because you only get them every 12 years or so," he said.
"But whenever you hear that the All Blacks are going to play the Springboks, there's always that element of mystique when the two sides play each other, it's still there."
Cooper, who said the All Blacks should win by 15 points, remembers sitting in the stands at Pretoria as the Springboks hammered the All Blacks line in the final seconds.
"To be there not only as a squad member but as a Kiwi, to have the opportunity to be in South Africa for that moment of time where history was being created was amazing."
The All Blacks go into Saturday's sold-out Rugby Championship match on the back of a comfortable 28-9 win over the Pumas in Napier.
The Springboks are looking to rebound from a refereeing howler that saw them lose 24-23 to the Wallabies in Perth.
The All Blacks have won all their matches against the Springboks at Westpac Stadium since they first met there in 2002 and haven't lost any game there since 2003.
By the numbers
NZ victories against SA at Westpac Stadium, Wellington
July 30, 2011 40-7
July 17, 2010 31-17
July 5, 2008 19-8
July 22, 2006 35-17
July 20, 2002 41-20