In a new twist this year, riders are permitted to ride their own bikes, rather than being forced to share the same bike and this means Groombridge and Hurley may campaign both the Suzuki RM-Z450 and RM-X450 model machines.
"We have not decided what bikes we will be riding, and we may yet share the same bike anyway, but both models of the Suzuki are capable of winning this race, so it doesn't really matter," said Groombridge.
"Whatever we decide to ride, I'm sure we'll be competitive.
"I've been doing quite a bit of riding lately, so my fitness is good but it's a different race to prepare for. We'll need to have spare wheels and things like that on standby, but really, I just ride it like a big motocross race.
"The trick is to keep your concentration levels up. One mistake and you're into a tree."
Groombridge and Hurley will come up against some heavyweight opposition, including current Woodhill Two-man Cross-country series leaders Josh Jack (Suzuki) and Luke Mobberley (Yamaha), from Kaukapakapa and Muriwai Beach respectively, as well as Auckland's former national enduro champion Chris Power (Yamaha), who will team up with Palmerston North's three-time former national cross-country champion Adam Reeves (Yamaha).
Yamaha's four-time former and current national cross-country champion Adrian Smith, of Mokau, Whangamata's former national enduro champion Jason Davis (KTM), Te Awamutu's Kevin Archer (KTM), Morrinsville brothers Hayden and Nathan Tesselaar (KTM), Morrinsville's Simon Lansdaal (Husqvarna) and Auckland mates Freddie Milford-Cottam and Mike Skinner (both on KTM bikes) are also among those expected to feature near the front.
Smith, with fellow Kiwi international Callan May (Yamaha) finished runners-up last year but May isn't competing this time.
The first solo rider to finish last year was Masterton's Reuben Vermeer, coming home ninth overall on his Yamaha YZ450F, and he may again be a contender for the ironman crown.
The iconic Suzuki Six-Hour will be followed the next day by the second annual Suzuki Junior Three-Hour race at the same venue, although the riders will be traversing a different and slightly less daunting route through the Ohakuri Forest.
The organiser of both events, Tokoroa enduro legend Sean Clarke, said Saturday's race would really "sort the men from the boys", and the course set out for Sunday would be "much more forgiving".