When Cracker Barrel Old Country Store Inc. bought Maple Street Biscuit Company last year, it promised not to tamper with the successful formula of the restaurant chain founded in Jacksonville. However, the company did make one change that is having a positive impact: opening Maple Street restaurants on Sundays. Cracker Barrel did not report sales data for Maple Street when the company reported earnings last week for its first quarter ended Oct. 30. However, in the company’s conference call with analysts, CEO Sandy Cochran said Maple Street’s comparable-store sales (sales at stores open for more than one year) were about 20% higher than a year ago.