Hey Hobbsy, I bought a fist-full of Fox Miracle plugs a while back and ended up giving most of them away.

We run 5% nitro around here and found that the Miracles were just too cold.

They'd run okay at full throttle but they made the mid-range run rough (as if too rich) and all the engines we tried them in would lose a couple of hundred RPMs when the glo heat was removed at idle.

Throw an OS#8 in and the engines were good as new again.

I'd say that (in practice) the Miracle *isn't* as hot as an OS#8.

I also tried the Miracles in my 4-strokes and they aren't a patch on the OS-F. They were good for a couple of flights but then they wouldn't hold a reliable idle any more -- almost as if the filament had lost some of its catalytic properties.

This was a couple of years ago and the fuel was 5% nitro, 75% methanol, 20% Castor/Synth blend (Morgans Pink oil).

We now use OS#8 or Fireball Hot or Medium in our 2-strokes and OS-F in our 4-strokes. They all work great.