Well, I figured I would post the first review. I got the Perrin Bar back in December. I installed it a few months later and that install is detailed in the DYI section. Anyways, I set the bar on the middle setting and have left it there. I have run three autocrosses with the bar as well as put several thousand miles on my car. The bar def. makes the rear of the car track better under hard cornering. Its solidly constructed and the Perrin drop down brackets are awesome looking. I don't have any other suspension mods yet so the difference in the cornering feel is all bar. I don't have the upgraded endlinks, so I am a little hesitant to put the bar on the stiffest setting. However, I have had no problems with the stock (04) endinks. I would absolutely recommend this sway bar, and whether you just do some mountain running or autocrossing the bar will help you enjoy the experience a little more...
Finally installed the KB endlinks I bought from M-Chan and set the rear sway to the stiffest setting. For the first time ever in my WRX I exeperienced oversteer! The feeling was great, something I have missed for a long time. I haven't yet installed my perrin front sway, it will probably tone down the oversteer, but, from what I understand, increase turn in response. Anyways, I still highly recommend this bar and def. recommend getting beefed up endlinks and going with the stiffest setting. *note: I drove miatas before buying the Rex, in the miata I was able to induce oversteer on demand and was very used to the effect and how to handle it. If you haven't driven a rear wheel drive car/ car with oversteering tendencies before, practice at an autocross/DE before cornering hard on the street. If you have never experienced oversteer in a vehicle before, it will suprise you and you don't want that on a public road....
lift throttle oversteer is nice (though it can be extremely dangerous if u dont know how to control it)... can definitely help cut some nice corners at the autoX