for what its worth adjusting the preload of the spring, front or rear only alters the attitude of the bike . it doesn't make it more springy, it only alters where in the suspension travel availible, the bike will work.
to make any bike more bouncy you have to either reduce rebound and compression damping and/ or change the spring rate ie get a stronger spring.
but you have damping for a reason
http://www.dfaulknersprings.com/
this is the company i use for my racebike cheap as chips
steve.