Hi. This is currently an academic question - I don't have a 'spare' motor to risk at present :) Would NOx catalytic converters become unnecessary on a 'spark' engine if only relatively cold air was made available at the intake? My thinking is that NOx formation needs high high peak temps and a lower initial temp could reduce (or stop) those conditions. I know there are issues with fuel vaporisation and condensation if air is too cold, but I hope we can come back to that later. Also I realise power is going to be required for refrigeration and I hope to discuss some ideas of how the cooling can be done for 'free' later. Initially I would just like to know what flaws my concept for negating NOx has (?). Thanks!