Measure 6 cups of mangos and put into a stainless steel pot. Add garlic, 1/2 cup chopped chili peppers to pot. Stir in brown sugar and vinegar.
Bring mixture to a boil. Reduce heat. Stir in Rum. Boil gently, uncovered for 30 to 40 minutes or until mixture is desired consistency, stirring occasionally.
Ladle into hot, sterilized half-ping canning jars, leaving 1/2 inch headspace. Wipe jar rims; adjust lids and rings. Process filled jars in a water bath at a full boil for 10 minutes.
Makes 5 half pints.