Sullivan won three Australian Under-16 Pairs Championships, first in 1989 with Brett Tomkins, and backing that up in 1990 teaming with fellow Adelaide rider Troy Norvil.

Sullivan was unbeaten in the heats to finish on 12 points before going on to win the final from Paul Schevienen and Troy Norvill.

Sullivan's also won round 4 of the 1996 Australian Speedway Masters Series 500 at the 510 metres (560 yd) Wayville Showground.

This would prove to be Sullivan's only Australian Championship win and the final time he stood on the podium of the event.

He returned to Peterborough in 2012 to replace the injured Kenneth Bjerre, but suffered a hand injury which ended his season and led to announcing his retirement from the sport in March 2013.

In his final shot at winning the title before turning 22, he improved to second in 1996 behind Poland's Piotr Protasiewicz, at the Speedwaybahn in Olching, Germany.

In 1997, Sullivan became the first Australian to win the Intercontinental Final when he led home an Aussie 1-2-3 (with Jason Crump and Craig Boyce) in Västervik, Sweden.

In both 1997 and 2003, Sullivan won the prestigious Golden Helmet of Pardubice at the Svítkov Stadion in the Czech Republic, his 1997 title being the first for any Australian rider.