1. Obtain some insulating foam tubing from American Science & Surplus
1-847-647-0011 , Item# 36465, 6 foot FOAM TUBE, $2.95 / EACH
http://www.sciplus.com/category.cfm?category=118
2. Remove the heater tubing from the Pinz, both the tube from the heat
exchanger to the control valve and from the control valve to the cab.
3. Slit tube along its’ length and place around the heater duct/tube on
the Pinz.
4. Next wrap it with 2 inch high temp aluminum foil tape, found in
hardware stores.
5. Reinstall heater tubes.
About 2 hours to install and very reasonable

I found that after installing the foam tubing insulation, I could drive in 30-35 degree temps with windows cracked open for my cigar.
I plan to wrap the exhaust manifolds and runners to the heat exchanger with header insulating wrap for even more heat.
Hope this helps
Tom E. 712M
Sonora, CA