had a quick chat with the shop just now.
first, they reckon they put it upside down on purpose, that's the only position that the tip will sit in the middle of the round hole on the rear bumper. and no NZ muffler has that drain hole. they'd drill one for me but they don't think it's necessary
secondly, they don't have the kind of silencer tube to put inside the muffler. the one we can buy off shelf here are those coming with big mufflers (i guess the common ones on ebay). i'll have to find some engieering people to make one if i really want to get rid of the 2000 rpm droning. ugh.