LOL...we all go through it and we learn from our mistakes. Many on here input based on their experience and mistakes.
In fact, I had a hard time getting the flange nut off so I also sprayed WD40, Corrision lubricant, brake cleaner, and PB Blaster on the stud and I am sure it got all over the pipes and perhaps the cylinder port....but the only difference is that I cleaned up the pipes and cylinder before I reinstalled.....so mine burned off quickly.

 

Freeze them for a couple days before install.

 

Someone else suggested that, good idea. I think I will freeze, apply a light coat of grease and sand the exhaust port edges lightly next time, if I can just remember. Actually I have had the exhaust off at least half a dozen times trying different pipes and mufflers and this is the first time I changed the gaskets. So obviously changing them every time is not necessary. Before I got these in I was wishing I didn't change them this time. I have had the nuts off & on so many times they were starting to gauld so I applied a bit of oil and they smoothed right out.

 

I use anti-seize grease on exhaust gaskets. Standard HD gaskets (cone) should work well on factory head pipes, but many aftermarket pipes use a different mating technique. Flanged vs. flat, where the SE (flat) gaskets work best.
cHarley offered a solution for loose exhaust flange nuts in this thread, post # 8.
https://www.hdforums.com/forum/sports...-stripped.html

 

I just swapped my exhaust back today after fitting the Cometic gaskets. I only ran it once, but i obviously didn't torque the bolts up sufficiently as it was leaking on the rear cylinder. I guess these are good, but you need to make sure the exhaust is seated properly and you squeeze it all down nicely.