Beginning in 2004, Duno competed full-time in the Rolex Grand-Am series driving a Pontiac-Riley Daytona Prototype for the Howard-Boss Motorsports team. Duno joined the SAMAX Motorsport team in 2006. For the 2007 24 Hours of Daytona, Duno teamed up with Ryan Dalziel, Darren Manning, and her regular driving partner, Patrick Carpentier; with a second-place finish, Duno became the highest-finishing female in the history of the prestigious race and highest placing Venezuelan driver, eclipsing Ernesto Soto's 5th-place finish in 1982. In the Rolex Sports Car Series Duno scored three impressive and historical overall wins – twice at Homestead-Miami Speedway and once at Le Circuit Mont-Tremblant in Quebec: With her first Rolex Series won at Miami she became the first woman in history to win overall a major international sports car race in North America, Duno was also the first woman to pilot the fastest car in the series – the Daytona Prototype. During her time competing in the Rolex Series Duno earned three overall wins, seven podium appearances, ten top-five finishes, and eighteen top-ten finishes.