Ummm well

1. Pure oxygen itself isnt flamable... Result from a fire is H20 + CO2, there is no C or H in pure oxygen therefore its NOT flamable (Fuel, C8H10 + O2 -> H2O + CO2)

2. Air itself is only 22% oxygen (N2O [NOS] is 33% ogygen. hence power increase) so if u feed pure oxygen in there, there would be a power increase