Crompton continued to race the Peter Boylan owned, ex-Satoru Nakajima Ralt RT20 in the 1990 Australian Drivers' Championship, though results weren't as forthcoming with his best place being a second in Round 5 behind touring car rival Mark Skaife at Oran Park and finished 4th in the championship. He finished his 1990 Formula Holden season on a high note, qualifying his Ralt (complete with its usual Dulux Autocolour multi-coloured blue, yellow, red and green paint scheme that was not unlike that of the Formula One Benettons) on the front row and then driving it to victory in the Thalgo Trophy Formula Holden support race at the 1990 Australian Grand Prix.