Comment on this story Comment Back-to-back wins haven’t stopped William Byron from believing he and his Hendrick Motorsports team have a lot to prove in Sunday’s NASCAR stop in Atlanta. In fact, Byron said Saturday, there’s even more on the line. Drivers of the Hendrick Chevrolets want to show the strong start to the season is not the result of illegally manipulating NASCAR’s rules. NASCAR slammed Hendrick Motorsports on Wednesday with the largest combined fine on one team in series history for allegedly modifying louvers, which direct air through the hoods of cars. The penalty included a combined $400,000 in fines — $100,000 to each of its four crew chiefs…