I am currently fermenting A hefe (extract recipe) and when I get to bottling plan on adding my Mandarin syrup - however.... If I double the 4oz of syrup to 8oz will that change the carbonating & cause exploding bottles?
You'll have to determine how much sugar is in the syrup. If it has any king of a 'Calories from carbohydrates' number, figure 100 Calories is about one ounce of sugar.