In 2008 he drove in the first two Grand-Am Rolex Sports Car Series races, including the 24 Hours of Daytona, in the Synergy Racing GT-class Porsche 911. He also competed in five FIA GT series endurance races in a Prospeed Competition Porsche 911 in the G3 class with teammates David Dermont, David Loix, and Franz Lamot. In 2009 he signed on to compete in the Firestone Indy Lights series, driving for Team E. However, the team nor Heylen never appeared on track all season. He attended the 2010 IndyCar Series preseason meetings with Conquest Racing but did not announce a deal with the team. However, the 2010 season saw him drive for Team E, which never happened in 2009, in the 2010 Indy Lights season opener in St. Petersburg. Ironically, he finished second, as he did in his final Champ Car race, to Lights rookie Jean-Karl Vernay. In 2011 Heylen drove in the 24 Hours of Daytona for Starworks Motorsport and made six starts in the FIA GT3 European Championship for Prospeed Competition and finished 27th in points.