geebus guys.
its not for looks, it doesn't even look good.
the manifold (header) heat shield is to retain heat within the header, and keep heat from the engine bay. its MAIN function is to keep heat in the header though.
the more heated the header, the faster the HOT exhuast fume exits the manifold chambers. we all know hot air molecules move faster than cold. right? right.
hence we have HEADER wraps that you can buy to wrap around your header. some aftermarket headers dont have a heatshield because they are either coated well in the inside or they manufacture choose not to. some have high heat coating... blah blah etc.
the problem with header wrap and headers with coatings to keep the heat in is... they wear out faster... that means the header will most likely crack earlier than a non wrapped or coated header...
thats why it comes out the factory with just heatshield, instead of wrapping the header completely with header wraps. (although header wrap works better, it'll definitely take a toll on the stock header)
and drag cars dont have heatshield because... well, they have open exhaust! I mean, the exhuast just exits right away... there's no path for it to travel... most drag cars or race cars have very short exhaust pippings.
