After Tasman Motorsports was sold in 1998, she was promoted to the role of chief engineer in 1999 and oversaw nine employees in its development, testing and race programmes. That same year, she had her second victory as a race engineer when Kanaan finished first in the 1999 U.S. 500 Presented by Toyota. Holl was briefly the chief engineer for Richie Hearn at the Della Penna Motorsports team during the 2000 season, before moving to Chip Ganassi Racing's R&amp;D division, where she conducted wind tunnel testing and was Nicolas Minassian's race engineer at the 2001 Indianapolis 500. Holl returned to the United Kingdom for personal reasons soon after and contacted John Barnard to enquire about a job. He asked her to telephone Adrian Newey and the McLaren Formula One team employed her as assistant engineer. She led a team of designers on its front suspension system and occasionally worked with its race and test drivers in the company's simulator.