I just had custom heat shields made for my pipe. I figure if the pipe is worth the power it produces then far be it for me to deprive it of a quality heat shield D
Made by @Pedro from the land of OZ
If I had a stock header and shield system and thought it was to hot I would find some spacers and longer screws to bring the shield out some. This will let more air circulate between them. I would not be afraid to go up to say 3/8" and attach some heat wrap to the shield via Permatex high heat form a gasket.