The sprocket and chain is smoother operating---although more challenging to install. I installed the arm & connecting rod on the Johnson Bar, but since is not traveling in a smooth straight line (like the chain set up), the horn arm is stressing the metal servo gears, and sometimes the arm movement binds. On another ACC engine, I installed the arm & connector rod on the throttle (it's very easy to install), instead of the chain & sprocket. Since the connecting rod is a little longer on the throttle than the Johnson bar, it is less binding--but not as smooth at the chain & sprocket. See attached pix. PS My recommendation is to do the chain & sprocket set-up first, to see if you like it.