As long as you aren't taking hot air from under the bonnet for a silly induction kit, reducing the temperature won't do much for you really....as long as your car's cooling system is running OK the engine will be OK without any further reduction in heat.
Exhaust manifold wrap...not easy on a turbo car. Works on NA applications...pointless on a turbo.
Inlet manifold wrap...not worth much if you are running standard ICs...they don't cool the air well enough for it to take any heat in from the engine bay!
If you have a decent FMIC or better, then wrapping may assist...but to be honest most of the heat in the inlet manifold comes from conduction from the head. You can fit an insulating gasket to reduce that...but they don't yield any power, so it makes you wonder why bother?
Again, on a NA car it is possible to get gains from taking precautions to prevent the inlet air from getting warmed as it passes through the engine bay...but that air can be at 0 degrees in wenter...you'll never get intercooled air anything close to that (maybe 10 degrees in winter if you are lucky!)
If you want a cheap mod, get some nice cold air into the airbox.