like franco2fly was saying on the muffler,hold the head of the bolt with a screwdriver while tightening the nut..thats what i end up doing..i took mine off the engine and lightly clamped in a vise so i could do that ...it made it easier..cause every time you tighten the nut without holding the other end,it turns the bolt untightening the tail piece..seems to work well for me so far...