Sloan said he surprised himself a little bit with some good times on the tarmac surface but said he felt he could have gone quicker on the gravel.
"I loved the tarmac stages, there is not many rallies that have the tarmac surface," he said. "But I know I have got more in me on the gravel."
Cox and Coatsworth finished the rally in a time of 1hr 16min 55sec, more than two minutes behind winners Richard Mason and Sara Mason (Masterton) and 14 seconds behind second.
Although Cox and Coatsworth placed first among the Rally Xtreme Series drivers on Saturday, Cox said he was still eyeing his maiden rally win.
"It is coming soon, we are getting closer and closer."
Cox said it was great to be involved in a rally which honoured New Zealand great Possum Bourne.
The Possum Bourne Memorial Rally featured New Zealand's top drivers from the Rally Xtreme Series and the New Zealand Rally Championship (NZRC).
After winning on Saturday, Mason has now moved ahead of triple NZRC champion Neil Allport to become the most successful driver in the history of the NZRC. He has claimed 23 round wins.
The Possum Bourne Memorial Rally started and finished in Pukekohe, Bourne's home town.
Cox said he was now looking forward to their next rally, Rally Wairarapa on October 5.