for return springs, I wanted a little assurance, so I used a spring on each carb (pulling up on the throttle shaft from the bottom of the air cleaner) and a third , longer-"softer" spring from the throttle cable barrel nut to the rear firewall. I've noticed that some system have the linkage toward the back (like mine) and some (like the triad) operating the carbs with the linkage toward the front firewall. I dunno which are better. I know I replaced my 20 yo weltmiester with the CB's aluminum setup specifically for 914s and it made a great improvement- got a whole package- linkage, manifolds, velocity stacks, air cleaners and they are apparently all tuned together- its really cool the way everything hooks up and goes bzzzz-bzzzz-bzzz instead of the previous UPS truck sound....