As it was Showtym's second show back from injury, the pair didn't have a great start in other divisions before deciding to enter the speed class.
Amanda said she hadn't expected to take out the title atop Showtym, which she bought sight unseen in Taupō about seven years ago.
"I thought we could be competitive, but there were some very good horses in the class and a lot of them put down some very good rounds," she said.
"Cassanova doesn't look quick but on the clock, he can run a pretty good course so it was a very nice surprise."
With the move south expected in the next six months, Amanda said she would miss life in Northland but looked forward to being closer to events.
"[In Northland] our closest show is three hours away and to get to [Hawke's Bay], which we do two or three times a year, is 12 hours so the travel time is just so difficult."
As the showjumping season had all but finished, Amanda said she was focused on preparing for the next season and to achieve her ultimate goal of representing New Zealand on the world stage.
"It would be an absolute dream," she said.
"Showjumping is something I'm very passionate about and I'm very interested in helping grow the sport by mentoring young kids."