Best tube dampers that you have used

Try going to the local O-ring industrial supply shop and buy some high temp silicon O-rings (usually white) you can get various sizes but taking a simple ruler and measuring the aprox diameter of the tube is all you need you can get various thicknesses to try. they work excellently and at the minimal cost you can experiment with different thicknesses.  this will tell you if spending more is going to be worth it in your system. I got a dozen of various sizes for under a few bucks. they are essentially the same thing as the custom guys sell for way more.