Something's not right - there's no way our pans would do anything more than simmer if the stack temp was 150 F. At 1900 F at the back of the syrup pan there's no way you can get that much heat out of the combustion gas in a 10 foot contact length. Maybe if you're running a piggyback pan system and routing all the gases through tubes in a secondary pan before the stack but not with a forced air arch.
Lapierre's published numbers from actual testing of their Force 5 is:
http://www.equipementsderabliere.ela...36/files/1.pdf