LAS VEGAS - The speed Kyle Larson found at Darlington Raceway, where he led 284 of 367 laps before finishing third, gave the driver of the No. 42 Chip Ganassi Racing Chevrolet a boost of confidence heading into the Monster Energy NASCAR Cup Series Playoffs. But what was the source of the newfound speed? Larson said something clicked during an Aug. 27-28 test at Richmond Raceway. “I felt like we had been ... I wouldn't say struggling, but we weren't running where I wanted to run or the team wanted to run,” Larson said on Thursday at Playoffs media day at South Point Hotel, Casino and Spa. “We were still getting top 10s and stuff, but I didn't see us being fast enough to contend for a championship.