@ KiwiMace, OMG that is funny!! scary due to the memories that came rushing back from those days of fortran and the like....still very funny. The guys here in the office now think Im nuts, laughing to myself, Thanks!
Louver losses/performace: I say measure it up, sketch the profile and go looking on the web for a similar product. Check Westvent, Aerovent, Greenheck was allready suggested. You will likely find the exact profile you have in which case the performance numbers will be identical to your louver.