Cold exhaust components??

[HotRoddin]

Ten minutes seems a little quick for them to cool down that much, but remember headers are relatively thin metal and there is a lot of surface area exposed to outside air, so they are going to cool off rather quickly if its cool outside. Also you don't generate much exhaust heat at idle.
You need to put a higher thermostat in there too. You're engine is much more efficient above 180 or 190, also your oil tends to sludge up more at that low a running temp.