The only Hawke's Bay driver in the Cowgirls team, O'Brien, is hoping for better luck than she experienced in last year's event which the Cowboys won after she experienced drive shaft problems.
Twelve pairs contested the title. Hawke's Bay's Brandon Symes and Phil Osborne were second and another host track pair of former national champion Jason Penn and first-season driver Simon Frater were third.
A highlight of racing in the 17-car superstock class was the appearance of Australia's three-time X Games gold medalist Blake "Bilko" Williams who was in Napier for today's Nitro Circus Show. While Williams didn't threaten the top three placings in any of his three heats he was full of entertainment in the car loaned by Hawke's Bay Hawkeyes driver Quintin Butcher and was more than happy to mix it up with one of the country's best blockers, experienced Hawkeye Mike McLachlan.
"I almost rolled Mike but he was too heavy," Williams joked to the crowd after his second heat.
"Obviously I don't know too much about racing in this class but when in doubt you go flat out. I think I held my breath for nine-and-a-half laps ... there was so much going on," Williams added.
Eight pairs chased the Best Pairs title in streetstocks. Hawke's Bay's Ben Yeoman and Wellingtonian Clive Rogers took it out.
The consistent host track combination of Tim Towler and Ben Darroch were second and another Hawke's Bay pair of Wally True and Ross Curran third.
Two-time national sidecar champions Russell Stuart and Andrew Parker of Hawke's Bay came from third place to win the four-crew final of the seven-crew East Coast championship.
"I can't believe the result. I suppose we are a little bit lucky those 1NZ blokes are not good on clay," 60-year-old Stuart said referring to Kihi Kihi's national champions David Gannon and Daryl Pearce who finished fourth.
"As we came up on the Gisborne boys [Rob Miller and Raymond George] I thought we can not give it a shot ... and it came off," the Palmerston North-contracted Stuart said as he outlined his last passing move for the title.
The Hawke's Bay pair of Justin Lincoln and George Olsen were third.
Eleven drivers chased the East Coast Production Saloon title. With first, second and sixth placings, Gisborne's Antonio McKay, won the title by two points from Whanganui's John Morrison and Gisborne's Matthew Schultz was a further two points back in third place.
There were two highlights in the 26-strong ministock class. One was Savana Peach's roll in heat two and the other was the win recorded by her Hawke's Bay clubmate Bradley Penn in the feature.
Another third generation racer, Penn, is the grandson of former New Zealand superstock champion Bryce Penn and son of retired two-time New Zealand superstock champion and this was his first win.