Matthew Dunn has continued his dominance of Highway races with Isla Tristana giving the Murwillumbah trainer his record sixth victory.

Dunn has achieved the mark in less than three months and Saturday's win at Rosehill took him past Terry Robinson and Matthew Dale who have five wins apiece in the races for country-trained horses.

Isla Tristana, who drifted to $6 before the race, made the step from a maiden at Ballina to a class two race, edging out Absolute Ripper ($4.40) by a nose with Tiger By The Tale ($10) two lengths away third.

"Wasn't she fantastic?" Dunn's wife Keira said.

The three-year-old filly was the sixth horse to prove they could handle the 10-hour float trip from the stable near the NSW-Queensland border.

"We've just got to ride the wave at the moment, it's amazing," Keira Dunn said.

Tim Clark took Isla Tristana to the tail of the field and stuck to the inside in the straight.

"I was spotting them a big start so I didn't think I could win coming around them," Clark said.

The win was the second leg of an early treble for Clark who picked up wins Pipeline and Dee Nine Elle in races either side of the Highway.

Dee Nine Elle's victory was the second time in as many races one of Clark's mounts got the nod from the photo judge.

"I wasn't as confident as I was in the previous race," Clark said.

"I looked up and saw Tommy (Berry) on the screen."