A tip from my days of playing with turbocharged Corvairs:
We used to wrap the exhaust up-stream of the turbo, but leave the down-stream side stock. By doing so, it would help retain heat w/in the exhaust where it was needed, spinning the turbo a little bit faster and therefore creating a little more power. (Basic physics - hotter the gas in an enclosed space = higher pressure.) Simple and effective.
The larger exhaust pipe on the downstream side of the turbo does the following: gas exiting the turbine side expands, which creates a cooling and vacuum effect, reducing back pressure w/in the system, which allows the turbine to spin a little faster, creating more power. Wrapping the exhaust side of the turbo with EHP or similar would defeat this process.
Biggest effect on cooling an MCI requires a very sophisticated variable device mounted 38' away at the front of the coach - providing, of course, that the cooling system is completely up to, or better than, OEM specifications. This variable device requires constant calibration, plus the ability to react to changes induced by instrumentation sensors in a timely manner. Failure to do so can rapidly create catastrophic conditions.
FWIW & HTH. . .