1.6 rockers

Going to a 1.6 rocker does not change the duration, the opening and closing points in drgees of cam/crank rotation are the same. What it does do is obviously open the valve deeped and because it has farther to travel in the same degrees of rotation it opens and closes quicker. This helps to trap more cylinder pressure=HP gain.

Running a 1.6/1.5 combo can help bring in the tork a littl;e sooner in the RPM range by increasing the avalability of fresh Fuel and Air during the overlap and by opening the exhaust the with the 1.5 it will increase scavenge allowing for a cleaner sweep of the combustion chamber....higher percentge of fresh A/F allowing the motor to burn more fuel = More Power.

Of course how much improvement depends on many things from compression to head flow but you will normally see about 25-40 HP on a well built bracket or hot street motor and it will improve low end tork by moving the tork band down anywhere from 100 to 500 RPM.