I purchased a pair and had difficulty installing. I gave up and began tearing down the engine for a rebuild.
I called Mac and they gave me specific instructions. I suggest doing the same. I'll try once more once the engine is back in the bay. They assure the headers will fit.
One thing to note. The number 8 cylinder pipe is not connected to the collector. I know it sounds wierd and I didn't expect it when I ordered mine. It slips on separately and is clamped before the collector.
There is a high-temp coating but it is not ceramic. The price is right but if I had it to do again, I'd spend a bit more and go for Hookers or Hedmans.