I have used Earl's with the "dead-soft" fillers. These work very well. But you can't reuse the inserts because they stick and tear when the headers are removed. They sell replacement inserts, but not sure how much. I would only use them if it is an application that you will not remove exhaust and/or the engine on a regular basis. I have had a set on my 91' GTA for a couple of years now without any leaks.
For my 81' Camaro, I have gone back to $15 Fel-Pro and am just as happy. Plus they can be reused a number of times. Ed www.edgesz28.com