RPG Pre-Runner install and frame horn ears

[Raptor911]

I am installing my prerunner and I need to enlarge the frame horn ears by 1/8 of an inch on one side. What's the best way to do this? An angle grinder is just too big. I am thinking maybe a dremel but the metal on the frame horn ears are pretty thick. I don't think a dremel is up to it. Any ideas?

 

[BIRDMAN]

Grinding cone drill attachment. Looks like this. Go to Lowe's