Here's a few idea's from the last few days of testing and riding,

I went out with my Avenger at the above temp and my new top, I also have the Argo optional heater. I found that the heater would blow lukewarm (at best) air, and only after 10 minutes of driving, it was okay inside, but NOT hot. I expected HOT air like a car to come out of the vents.

So into the garage we go, I taped over about 3/4 of the exhaust vent with tinfoil tape (used for ducting) and also used the old school car trick...... Cardboard with a 5-6" hole cut in the center in front of the rad.

Next day out for another ride, not as cold this day about -22c (-8F) but WOW, it wasn't long before the jacket was off and the drivers door was part open. Next off came the tinfoil tape. I found that just the cardboard was enough, the air out of the vents is HOT now and when left to idle it stays at 3 bars on the guage and continues to blow HOT air. It's a world of diffrence, in this warmer temperature it would hit 4 bars when running across the ice for long periods and the heater fan off, so I would just kick the heater fan back on and Whammo, back to 3 bars. I don't expect that problem when the temp drops more though so it is set pretty good for now.

If it runs cold in REALLY cold weather I will just tape the exhaust back up a bit.

The other big thing I noticed is that the heat coming through the front engine panel into the cab was cool before and now it is hot, like in the summer, so I am getting the engine temp up where it normally is and that gives a lot of heat into the cab alone.

PS
We were the first people to travel across the lake yesyerday up here... 1 more advantage to an ARGO!! Cut a couple random holes and there is about 6" already !!!