a couple things; The brakes as you continue to use them will wear the zinc and start to seat more allowing more stopping power. Make sure the Ebrake cables are setup and properly adjusted. Also prior to that ratchet the rear levers back and forth till you feel alot of resistance(this means they are adjusted) hook up the cable and adjust the tension. Also, a booster of any size needs a minimum of 18" of vacuum to properly function. This really matters more when a smaller booster is used.