what about for keeping temps cool under the hood, with stainless headers is coating worth any heat reduction?

The heat reduction is HUGE underhood -- particularly if they're coated inside and out (which they should be).... Then the heat gets expelled.

If you don't like the look just have them coated.

Brown or silver.

Just the reduction of under hood temp is worth it.

Sweet!

These are uncoated stainless headers on my Corvette. I personally like the patina.
http://i162.photobucket.com/albums/t...ps33b63506.jpg

My Camaro headers are 15 years old and coated mild steel.
http://i162.photobucket.com/albums/t...s67c0f24e.jpeg