I've had my muffler fall off 3 times. So do yourself a favor. Go to the hardware store and buy yourself some new bolts that are long enough to go threw the muffler and threw all the threads of the head on the motor. Also buy some washers that will fit in the muffler bolt holes. Also get some red lock tight or some other permanent loctite. I've had to buy an 80 dollar Heili coil set because I thought I new better. Do what you want. But if you don't do it right you will be back on here asking me where I got my heili coil set.