Buddy club racing spec condenserII has anyone tried?
 

My brother gave me this today... I did a little reading seems like it's a voltage stabilizer and grounding kit... Has anyone installed this on their z? Is it worthy time to install it or is it just a bunch of crap?

It is not going to help your audio. If you want to help that do the "big 3" just google it. This seems to be more for ignition and engine block ground.

Also that will only improve your system if you have amps in it.