I had my peakboost turbo manifold coated with black 2000* cermaic coating, and it did not hold it heat as well as the thermotec copper stuff on my 3" DP.
If you do coat go with Swaintech white lightning on the exh. But wrap is more then good enough.
For the I/C piping the foil heat blocking wrap works better then header wrap, since header wrap keeps heat in. The foil looking stuff reflects the radiant heat. I had it allover my firewall in my s13, on the brake resevoir and coolant tank and it works great.
The header wrap on my dp kept my ass form burning under the car too and the heat shield on the firewall did great to keep the heat out of the cabin since I had no carpet or anything, just metal.
Wrap works hands down no questions. So does heat shield
On a turbo app it is great, the way to bump efficiency is to make the in/ex temp ratio greater. The cooler in and hotter out is the trick. Anything to help achieve that makes more efficient use of all your mods, not to mention electronics hate heat, so lower under hood temp is 2 fold. Lower intake temps and longer life on the electronics.