i have a 05 sedan non sport with an 07 Z full suspension. im finding the ride a little too stiff for me.

here are some options im considering for the rear suspension:
1. coupe springs/z shocks
2. coupe springs and shocks
3. eibach pro-kit all around with non sport shocks

which one of these will be the better option? im just tired of going up and down the freeway with people in the back seat bouncing up and down.