what are goals?what deck do you have a tall or short?how much torque you want?budget?you kinda gotta tell some specifics of your combo?boat drag street what?ive got a 572 10:1 compression with roller cam and love the torque....the bigger the better as long as the bigger torque will hook up if its a drag application.just remember the more you wander from the 1/4" increments of the stroke the harder itll be to find off the shelf pistons!i wished 4.625 stroke combo in a tall deck combo was more readily available.