Do some winter flying in below freezing temps. Original plans muff on right rear exhaust pipe provided some heat but not enough.
I ducted heat from the top oil cooler into a small muff on the front exhaust pipe then into the stock muff and then into the cabin. Keeps me warm. Very comfortable in the upper 30s throught 60 degrees F conditions. Have retrack gear with rip-stop nylon muffs on the spring bar and the elevator push rod through the rear spar, so no drafts in the cockpit.
