The Starcraft mare joined McKay's stable from Cambridge trainer Stephen Marsh earlier this year with a record of two placings from seven starts.
''I really like her - I rate her quite highly,'' McKay said.
''The thing is when you go back through her record, they seemed to have been targeting the $12,000 maidens and $20,000 maidens with her [in the North Island], so they obviously rated her, but she does have a mental issue.''
McKay described the 5yr-old as an ''unusual budgie'' who did not always treat the barriers as her friends.
''She's not the full quid. Ability-wise, it's all there, but it's just what she does at the start of the race.''
The problem popped up again at the Gore trials on Sunday, but it did not stop her going on to win the 800m trial with ease.
Another former North Island galloper is a winning hope for McKay in another 1200m maiden. Superior Knowledge began her career with Cambridge trainer Lisa O'Shea and debuted with a third at Winton on September 18. But the good track will be an interesting test for the Fast `N' Famous gelding, McKay said.
''He's a nice horse, but he's still got a lot to learn. He's really green.
''When he trialled in the North Island, his trial here, and his race here, they've all been on heavy tracks, so that's one thing we don't know about it.''
Final Wave is a first starter for McKay in Our Supernova's race, and McKay would not be surprised to see her feature on debut.
''She had a trial the other day and went nicely under a very heavy weight and nothing would surprise me if she was figuring in the finish. McKay expects the Coats Choice filly to find her niche over more ground, but the 1200m would be ''a good education for her''.
McKay has two chances in the rating 65 1200m and is leaning towards Hermione, a deserved maiden winner at Winton last month, over No Mean Feat.
''She's probably going to be a bit better over more ground in time, but she's quite hard going up until now, so we've kept her to 1200m. She'll have a huge show.''
Of McKay's other starters, she expects the mile to suit Gallivant (race 1), while she hopes Kung Fu Panda (race 5) can win a maiden race before his career ends.
''The mile will suit better but he's a day-by-day proposition [because of a breathing problem]. I keep saying this is his last start - he should be getting his name changed to Just One More, I think.''
Top Wingatui gallopers Ric O'Shea and Ridley resume preparations for their spring campaigns in the open 1200m. Ric O'Shea was impressive in winning a jumpout at Wingatui late last month, with Ridley doing his best work late to run second.
Ric O'Shea's trainer, Steven Prince, has engaged apprentice jockey Courtney Barnes for the ride, to take 2kg off the gelding's carded weight of 59kg, while trainer Joanne Hillis has engaged Shankar Muniandy for Ridley.
