I agree with bferullo. I've messed around with maple during the boil, during secondary and during bottling. I've never had more than a touch of maple flavor/aroma with any of it. I probably wouldn't even know it was in there if I didn't do it myself... Bottling is probably your best bet if you want to taste it. I think maple syrup is around 60% sugar? I would check the sugar content per serving of the syrup you have and calculate based on that vs. normal priming sugar.