GTS action returns this weekend for rounds 16 and 17 of the 2016 Pirelli World Challenge. There are only four races left in the 2016 Pirelli World Challenge GTS championship to decide the next driver, team and manufacturer champions. GTS championship drivers will compete Sept. 16-18 at the legendary Sonoma Raceway in California and will share the track with the Stars of the Verizon Indycar Series competing in their final 2016 round. ANSA Motorsports is taking three well-prepared KTM X-Bow GT4 machines to California for the last four rounds to be raced at Sonoma and at Mazda Raceway Laguna Seca (Oct. 7-9). ANSA Motorsports’ driver lineup includes Bill Ziegler, who will be behind the wheel of the No. 9 Swisher Racing KTM, Hugh Plumb driving the No. 12 KTM, and Brett Sandberg, driving the No. 13 KTM. Sandberg travels to Sonoma, California, with ambition, and hopes to do well on the 2.52-mile road course, located on the landform known as Sears Point in the southern Sonoma Mountains. His primary goal is to continue to score maximum points, so he can get to the season finale at Laguna Seca, California, and give it 100 percent hopefully to win his first Pirelli World Challenge GTS championship. Sandberg currently leads the GTS championship with a 66-point advantage over the second-place driver. "Coming off a solid points weekend at Utah Motorsports Campus, I am extremely excited to race at Sonoma Raceway, as this is a track where I have been racing well for years, and I believe our nimble X-Bows will be more than competitive at this venue,” Sandberg said. “Leading the points at this stage is certainly nerve-racking, but I believe in our team's capability and am confident that they will give me the best car to go after this championship!" Plumb returns to ANSA Motorsports and gets another opportunity to shine behind the wheel of a KTM X-Bow in a series that he knows quite well. At Lime Rock Park, Plumb did not get the result he deserved but at Sonoma Raceway, the very experienced driver from Unionville, Pennsylvania is ready to run at the front of the GTS pack. “I am grateful for the opportunity to rejoin ANSA Motorsports this week at Sonoma Raceway,” Plumb said. “I am hoping to put the car in the front as we were the last time I was able to drive for them at Lime Rock Park. ANSA Motorsports is a great group of talents and professionals that know how to get the job done. Hopefully, this time we can put the ANSA Motorsports KTM on the podium.” Plumb competed in the Pirelli World Challenge Series between 1998 and 2001. In his four Pirelli World Challenge seasons, he scored four wins, 15 podium finishes and 30 top-ten finishes and helped collect two manufacturers’ championships. Ziegler, from Ponte Vedra Beach, Florida, racing under the Swisher Racing colors, continues his 2016 season and, like his ANSA Motorsports teammates, should be able to take advantage of Sonoma Raceway’s twisty course to drive his KTM X-Bow to a top-ten finish. For ANSA Motorsports as a team, Sonoma is also an important race weekend, since the team currently sits third in the team championship, only 46 points behind the championship leader, and with three KTM X-Bow cars entered in rounds 16 and 17, everything is still possible to win the title. Practice for the Sonoma Raceway event starts on Friday, Sept. 16; Pirelli World Challenge GTS competitors will have two sessions -- at 8:45 a.m. and 12:30 p.m. Qualifying is set for Saturday, Sept. 17, at 12:45 p.m. Sonoma Raceway GTS race 1 (round 16) is also scheduled on Saturday at 4:50 p.m. Sonoma Raceway GTS race 2 (round 17) is set for Sunday, Sept. 18, at 10:15 a.m. (all Pacific Daylight times). Don’t miss both races live at World-challenge.com. The Pirelli World Challenge GTS Championship rounds 16 and 17 at Sonoma Raceway will air on CBS Sports Network, Sunday, Oct. 2, at 5 p.m. EDT.