If you use a razor blade to score the muffler tip all the way around it about 3 times, one ziptie will work. The cuts give the deflector something to grip, and definitely clean it first. I've had mine on with on ziptie for quite a while, and I can't even rotate it after its in place. If you want the end all solution, go to the auto parts store and get the small hose clamps for it. They can be tightened up a lot and you can practically hold the weight of the plane from the deflector.