Just a heads up for those who need intake valves that will live at high temperatures.
As tested on some of the hardest-working Miata engines on the planet. – Flyin' Miata (flyinmiata.com)
These are back in stock with Flyin Miata.
I've been waiting over 18 months.
After I ordered my set, I called them and verified they have 48 more.
That's just six sets guys.

If you're looking for indestructible intake valves these are the ticket IMO.

I've pulled their Inconel exhaust valves out of a head that had detonation marks in the combustion chambers and destroyed SS Supertech intakes.
The exhausts were so "un-touched" that I could tell they hadn't been lapped in during assembly.
25+ hours of abuse and they looked like they just came out of the box; even carbon doesn't seem to stick to them.
I was able to clean them up perfectly with a bit of B12 and a paper towel.
SOLD me on Inconel as the best valve material...

I believe Jmann on here is running a set and is completely happy with them.

 

I bought some last time they were in stock. I’m currently running the Manley sst intakes and the ST inconel exh. At 20kmi I will freshen up the engine and install them. I have adjusted my valves and have not seen much movement from the intakes. In fact they are fairing pretty well after 3-4kmi.