Is this the "thing" with packing? Just like tranny oil, just change it often? The crap that fmf sells is cheap, like most oils. Over a year it can get pricey, in a pinch? As long as it does not catch fire, or blow asbestos out the back, what the heck? I believe the word is resonance. I know the correct sound, and the throttle response matches. I could really use a strip of that stuff to keep my plastic tank from melting on my 480! It looks like the same stuff I use to sweat copper and not burn houses down. And its really expensive! Vintage Bob