what is the purpose of this? is it really needed?

 

Go drive your car really fast.. like boost the crap out of it.. Then quick get out and run and touch the manifold... hotter than ---- isn't it??

Heat shield = Looks, shields the heat (that is why they are above the exhaust under the car). If you dont have anything that will get burnt by the exhaust, (like if you have an amp wire laying on the engine... dont laugh I have seen this before..) Then you may want a heat shield to protect that precious amp wire Other than that.. you could put it on for looks if you wanted too.. just so you dont see a bad weld.. or something to that extent.

 

Or the exhaust could be radiating so much heat that your paint on the hood starts dying...?