I think Jan's shield wil help keep the hot air from going up and everywhere under the bonnet a bit better. It's probably trivial since it's not a sealed air thing and the turbo is unshielded, but it may just help. Another thing you can do is wrap the manifold and/or ceramic coat it on the outside. Don't coat the inside. If it starts to flake, the flakes will wreck the compressor of your turbo.