Has anyone added just an aftermarket rear sway bar?

[SennaZ]

My friend, with his S13 just added some cheapo large rear sway bar, leaving the front standard i believe. The intention was to increase horizontal movement in the rear, and kill vertical (roll), for the car to become much more, er, oversteer-y. And it worked. Turn in is much more neutral now and you can feel the rear want to controllably rotate at higher speed.
I'm in the process of picking out a coilover kit for my 370z and thought what if I did the same, and just bought a rear bar only for the Zed.
Has anyone upgraded only their rear sway bar?
or do you have to do both pretty much