With my new coming vehicle I plan on using a belly pan. What do you do with the exhaust? Do you cover the exhaust system with a pan and wrap it in heat wrap? Will it make the floor pan so hot the carpet will melt? Or do you build the belly pan up to it and leave it exposed? I also thought about puting cone shaped pieces like you would find at a Home Depot for chimney vents around the muffler for the aerodynamic bullet effect.
On my belly pan, the covering under the exhaust system is aluminum flashing. I designed it so there is an air flow running from the engine compartment through the enclosed exhaust tunnel to keep it cooled. Its been in place for almost 2 years without problems.
The aluminum screen is cheap, fireproof, breathable, and apparently pretty easy to install. Does not rattle or boom like sheetmetal. So, use it around the hot spots like mufflers and exhaust pipes, to let hot air be drawn out by Venturi effect. Also, being a superb heat conductor, it will very efficiently dissipate heat from any point of contact with a muffler, etc.. Even though porous, the screen will still go a long way to reduce improve form drag, i.e., streamline or smoothly cover otherwise gross aerodynamic shapes such as leading edges of mufflers, etc.. Porsche uses perforated screen as an engine cover on its latest high performance mid-engine car, the Carrera GT.