Place popcorn and pecans in a large bowl; set aside. In a large heavy saucepan, combine the sugar, butter, maple syrup, corn syrup and salt. Cook and stir over medium heat until a candy thermometer reads 300° (hard-crack stage). Remove from the heat; stir in maple flavoring. Quickly pour over popcorn mixture and mix well.
Transfer to baking sheets lined with waxed paper to cool. Break into clusters. Store in airtight containers.