Could you make a test with 2096 and 41005/41001 header?
next weekend I will test those combinations out.. its 22* and snowing out here in wi usa.. but a long 7 hour drive next week to test for 2-3 days and will have a better answer also..
on plugs I have been using the gsr p5 plugs and in the really cold temps the gsr p4.. basically os plugs.. the gsr 5 is pretty close to the ct06 nova plug but half the cost