well, rsb is next on my list so i was wondering if there was any difference between these...the addco is cheaper by about $70...any difference?

Hehehehe... you know what I'm going to say.

Stillen will definately be an easier install. I have addco (though I took it off for what I thought was an alignment problem on my rear end). I got a thunk occasionally on weird bumps. I personally don't want to give stillen any of my cash which is why I went with Cattman/Addco. Performance increases were very noticable. I have to reinstall my bar and see if the noise goes away with proper installation (last time I couldn't get the car up on my jackstands).

Hope this helps