thermo wrap definitly works , it works too well ,in racing cars we have used it on the extractors only last 12 months at best , and exhaust shops round here dont offer any waranty on systems if it is used ,i think it works by creating a buffer of hot air around the out side of the pipe which decreases the amount of temp lost to the engine bay .
To me the flange is creating a restriction before entering a larger pipe which will by nature increase the temp substantually on the right hand side of pic so before i can draw any conclusions i would like to see a before pic . Djr81 you may be correct but with the evidence before us it is unconclusive.
Just my 2 cents . interesting discusion ,thanks.