What happens when a coil starts to go bad?

[osu_josh]

My bike seems to feel like it hits them rev limiter really quick? I have a aftermarket box that lets it rev a 1000 more but it still feels wrong. Someone told me my coil my be bad or not keeping up with everything else. Any suggestion welcome and thanks for the help in advance.
Josh

[WilRideAnything]

I personally don't like aftermarket CDIs. Try putting the stock CDI back and see what happens. Have you changed anything recently?

[eastside 400]

a bad coil will just miss