right true it is a part of the exterior of your car but... if you read the descriptions on the forum lists youll see that under exterior is for "Aero parts and exterior appearance modifications, (body kits, wheels, lighting, paint, graphics, etc)" while the Engine forum is for "Anything to make your car go faster or handle better (Engine, Exhaust, Suspension, Tires ...etc)" and Im just letting you know so that you can better utilize the great ecelica site. and don't sweat it for everyone here has had some screw ups here and there.
but now back to your question you can get one off of ebay for like 12 bucks, but seeing how the heat shields are just a piece of metal i doubt that it'll make a diff. between the diff. costs. [/color]