The purpose of the heat sheild is to keep the underbonnet temperature down and also to protect the surrounding parts of the engine bay from heat soak , the first one effects performance , the cooler the engine bay the better the car runs by allowing cooler more dense air to enter the engine giving a better burn and hence better performance , the sheild also protects surrounding ancilleries from heat soak or radiated heat which will soak into the nice black plastic induction box heating up your intake air which causes the first problem mentioned , you will see the effect of this if you take out your dipstick (which passes between the exhaust headers) you will notice that there is a dark patch in the middle of the dipstick that is incinerated oil stuck to the dipstick due to the heat soak from the headers. (Description by Bert Reid).

10mm spanner

medium screwdriver

patience

Many parts of the engine bay become extremely hot every time the engine is used, make sure the car has not been used recently before attempting this project.

STEP

Remove the screws retaining the air duct (marked in green).

Remove air duct. View with duct, PIC 1, without duct PIC 1A

Remove 3 nuts from heatshield (red, pics 1 & 2)

Pull heatshield up and out, levering the left side forward and away from oil feed pipe.

Pic 3 shows the likely extent of damage, symptoms being severe vibration noise. PIC 3A shows the engine bay with the heat shield removed.