I wonder if it could be a case of EPA type regulations being relaxed lately. I know years ago when I got my manifolds re-porcelained by a local company, the owner warned me it wouldn’t last because they weren’t able to use certain ingredients any more.
They looked gorgeous at first but cracked up after about a year. In comparison, I once had an 50,000 mile XK150 which still had perfect porcelain on the original Jaguar manifolds.
I’ve been on this forum over 20 years and never heard before that anyone can successfully replicate the original porcelain, so what’s changed?