What caps you asking about on what saw?Talk about why changing caps?
On the Echo saw, and many others there are limiter caps on the high and low carburetor screw's. These caps only allow so much adjustment to keep you within the EPA specifications. If you search removing carb limiter caps you would find a few videos, generally a fine treaded wood screw can gab the cap and if your in the correct position you can pull it off.You wrote pulling the one EPA cap left to get more RPMs. I took that to mean you were replacing it. How does that help RPMs?