Round Six of the American Iron West Championship Series took place at Thunderhill Park Raceway in Willows, CA on September 6-7, 2003. Racers in attendance were Tim Nichols, Bruce Griggs, Bill Daffron, Ernesto Roco, Tim Gilpin, Christine Knight, Guy Cunningham, Terry Buch, Keith Videtto, and Paul Mashouf along with newcomer Eric Knudstrup. A "mystery driver" was also slated to drive the #34 Total Control Products entry on Sunday, but the veil of secrecy kept the crowd wondering until a certain notorious racer was seen in the vicinity of the TCP pits on Friday afternoon.
In Saturday qualifying, Terry Buch scored the AIX and overall pole besting Tim Nichols by a scant .124 seconds. Guy Cunningham took the AI pole with a scorching 2:00.036 lap time. The race began with a standing start that saw Buch and Nichols break out to an early lead through the first few turns. Buch eventually shot out to a 5 second lead over Nichols, who had established a nearly 20 second lead over Griggs in the next spot back as the race neared its final laps. A bad shunt involving two ASC entries oiled down the back section of the track with three laps to go, which bunched up the field behind the pace car and cut down the lead that Nichols and Buch had established. The course went green for the final lap and Buch managed to hold on for the win with Nichols just behind and Griggs in third. After Cunningham was felled by an electrical problem during the race, Keith Videtto turned in an excellent performance to score his second AI win of the year with Tim Gilpin and Eric Knudstrup taking the next two spots.