I agree with the 'no foil' crowd here.
I have mopped with a red pepper vinegar sauce that has added some real bite to the bark, but it is not needed. Also look into the amount of sugar in your rub.
-Santa Maria Grill
-20,000 BTU Bayou Classic Charcoal Starter
-22.5" Weber Kettle
-Fish the dog-Loyal Team Mascot
"You go to the BBQ Competition with the BBQ you have, not the BBQ you want"