Pit and chop plums to measure 10 cups. Combine the sugars, vinegar, mustard seed, five spice powder, chile peppers, salt the garlic and the ginger root in a non reactive(stainless)pan of pot. Bring this to a boil and then add the chopped up plums, return to a boil, and boil gently(rolling boil) stirring every once in awhile for between one and two hours, or until thick. Fill a boiing water canner with water, and place about 6 clean half-pint mason jars in the canner, and keep the heat high...ladle the sauce into a hot jar, leaving 1/4 inch head room and remove air bubbles with a hot knife or spatula along the sides and re-adjust the head space to 1/4 inch...wipe jar rim to remove any sticky stuff, and place a snap lid on the jar, apply the screw band until finger tight, and place the jar in the canner, repeating for all remaining jars...cover canner, return water to boil and process about 10 minutes at altitudes up to 1000 ft. Remove jars, and cool for about 24 hours, then check jar seals to make sure they all went down, and any that do not, use right away, and store in the fridge...those that seal, and they all should if you do it right, label, and store in a cool dark spot in your cupboard. In our opinion after the taste test tonight, it is as good(better)than the store bought stuff.