Originally Posted by
Dr. Johny Dodge
with the Lengal plenium I'd consider making the spacer a simple rectangle instead of cutting it to the shape of the gasket - then it would also block the plenium from any "line of site" heat transfer from the exhaust castings below
by nature that polished aluminum can is going to collect and store heat
leaning on the polished fins on a black valve cover shows the difference in heat retension / transmission of polished parts vs black painted ones