Simple- - - -the drain hole goes to the rear, and the muffler is intended to be installed very slightly rear-low to allow condensation to drain. Otherwise the muffler rusts out quickly on cars that don't get run long enough to heat up and evaporate the condensation that accumulates on a short trip. Yes, it will muffle effectively with the exhaust flowing either way, and there won't be any difference in back pressure.
Salt or pepper with that hat? How about some hot sauce?
Jerry
assuming that that are a caddi specific muffler, then that may not always be true, ALOT of caddis have the mufflers mounted swept up in the back, thus the drain hole is in the front below the inlet.
