The rear is worth every penny... it made the most difference of all my mods I think. I haven't put on the front... Brian (Tuned200) helped me install it.
It tied the rear together, and made it more trustworthy/agile in the corners... I also felt like it spread loads along the rear well. like if a bump was felt on the right side of the car - some of that load is transferred and spread out... making for a smoother ride.
Just my personal experience. My fav suspension mod for the money.
I'm riding on GC's/AGX's, Cusco FSTB, Rear Ebay STB, & the ST in the rear... I have a front tie bar in my trunk but I've been too lazy to install it.