I like Carbon effect or real carbon on an Exhaust, for the main reason it is safe to touch that part of the exhaust when up at full working temperature, cannot do that with a stainless steel exhaust, without scalding your fingers or leg.
Image below was of my carbon effect exhaust on my GTR1400, bought from well known manufacturer, like said safe to touch and hold a hand onto it, for long period if need be.
Plus INMO looks cool, and much lighter than most metal or stainless ones.