this past weekend i went to my uncles house and we were discussing what we had planned for each of our cars (his car is a '03 BMW M3, obviously mine is the Z28) and i mentioned that i was going to put a catback on it. He told me that if you put some sort of thermal/ceramic coating it would actually improve performance because it would keep much more of the heat within the pipes, thus increasing exhaust gas velocity....Now I have no clue if this is true or not, and if it was true, if the effect would even be worth the cost of coating the catback but i am interested in the possibility. First of all, it would probably make the exhaust look much nicer, and it would also increase the life of the system too. I'm just looking for some feedback on this theory and how it could be applied to my car, and other third gens.

Note: I do trust my uncle when he spits his knowledge of automotive performance because he used to race motorcycles back in the 90's and built many champion top fuel drag bikes so I would imagine he knows what hes talking about.