Get a neck brace..
Use default profile smooth at first and if its trackIR5 take note of the program and how the graphs/sliders work in relation to your head movement then adjust if necessary..
when in TrackIR program..goto views and select 'Show HUD' it gives you a 'mock' cockpit and allows you to see what your head movements are doing in relation to the game and you can adjust as required..
hth