I have seen the manifold spacer you mention and no I didn't. I'm oem man too. The spacer is meant to insulate the manifold from heat soak from the block.
But with all the surface area that is in contact compared to the surface area exposed to the heat in the engine bay I really can't see the point.
The site selling it also hasn't proven any gains from fitting it.
Furthermore fitting the spacer marginally changes the inlet tract length which could have a positive or negative impact on performance, but with out dyno runs to back up the claims I'll steer clear.
As to heat we both were messing around last night after some test runs and took some pictures with a heat cam.
