Defroster solution! :)
If your defroster / heater performs pitifully in cold weather check to see if it's got a 5/8" valve installed in the 3/4" heater hose. Mine did so I replaced it with a 3/4" valve and even added another 3/4" valve in parallel with the main valve by using a "Y" on either side of the cable operated valve. The second valve is manually operated and I'll leave it wide open until I get to a warmer climate. Also notice that your heater core may be 5/8" instead of 3/4" like the hoses. In my case there was a restrictive 5/8" to 3/4" adapter on either side of the heater core, which I removed and clamped the 3/4" hoses down hard onto the 5/8" heater core. Check it a few times afterward to be sure it isn't leaking. The performance improvement is noticeable. I haven't used the defroster yet since I made this modification but there's definitely more heat now! 
Also there's hot water circulating through the heater core all the time when the manual valve is open so I have instant heat anytime I turn on the heater. It used to take several minutes for the heater core to warm up because the engine is 30+ feet away from the heater core. I also insulated the defroster ducts but I haven't had a need for the defroster yet so I can't say whether that had any effect or not. Maybe I'll report on this later if anyone is interested... Hope this makes someone's Winter driving safer and more comfortable.
Topic: Defroster solution! :)