The aftermarket filters that are used for CB750/CBX are not the same quality as OEM Honda filters. I have a CBX also and a service bulletin warns of using even an old stock OEM Honda 750 filter in it. If you compare an aftermarket filter side by side to a new stock Honda filter you can see that the Honda has more pleats in it. There was also evidence that aftermarket filters were collapsing after a few hundred miles. All new Honda OEM filters are now upgraded to one type that works with even the CBX. For the small price difference, I would go with the new Honda part.
