really,really hot!!!!!

[Serum]

btw; if an airfilter is closed, the motor will run richer and therefore run cooler. rich means less air (since it can't breath, it's getting less air) a clean filter means more air, so leaner, which means more heat. You don't tune an engine with an airfilter, but you do tune an engine with the airfilter on, so if it ran okay with a clean filter, it will run richer with a dirty filter if the same settings are used.