Mike,
The Kohler Command (and basically every other newer V-twin engine) was subject to more strict emissions regs than the Magnum and previous engines were, so they have a fixed jet carb and run lean, which means they run hot. The heads also don't have a ton of cooling fins, so the engine is relying mostly on intake air charge and oil to cool the heads.
To accomplish this, the firewall needs an additional piece to close out the bottom of the frame such that when the foam seal between the flywheel shroud and firewall is installed, the flywheel can only suck cool air from behind the firewall. Without the firewall sealed off well, hot air can wrap around and heat the intake air, which lessens the cooling of the heads. A lot of people cut the air filter cover on these installations so that the cover can be removed, but this will cause the air filter to draw in hot air from the engine compartment instead of cool air from the flywheel inlet. I will either not cut the air cleaner cover and deal with removing the gas tank to service the air filter once a year, or make a new cover with a snorkel up to between the headlights to draw cool air from outside the tractor through the headlight panel.
I also bought an oil cooler for the larger Command engine that I am planning to install with a separate duct and a small electric fan to blow cool air through it. Most of the oil cooler installations I have seen on these engines are more of an oil heater, as they are just relying on passive cooling in a hot area of the engine compartment.
