Your description of the orange gunk is very apt. It DOES smell like salt and vinegar chips! Glad all these people are popping by to tell me how much success they've had with the crap. All I can say is kudos.

I've only tried applying it liberally to both surfaces, having cleaned them completely of all grease, splooge and old blown orange crap from the last unsuccessful application. New heads, new pipes, new springs. Waited longer than 72 hours or whatever the tube says. It blew out. Why? If anybody suggests I'm doing it wrong I'll break yer arm!

Fact is the sprung exhausts vibrate and flex. The pipes on the nsr aren't held ridgidly to the motor and frame. There is movement, especially if you aren't running rear hangers. I would suspect that people having all this luck are running them except I know most people ditch them so I don't believe they are. Sure, you might get a seal happening, but hit a bump or bump the end of the cans with your leg when you get on the bike and you'll notice the lever action will break the seal at the head as the springs flex.

I only recommend trying silicone instead as I have had success with it plugging holes in car mufflers! It''s totally different but I imagine the silicone would take more flexing before breaking the seal and you can apply thicker amounts of it.
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MC21 Honda NSR250. TYGA 300 conversion.