It is most certainly worth it. Not only does it improve traction and eliminate peg leg, one wheeled burnouts, but it allows torque to be transferred to the wheel that needs it. When cornering, an LSD also allows the wheels to rotate independantly, in that one wheel, in a turn, will spin a greater number of times than the other thus improving cornering acceleration plus saving rubber on your tires. Probably the best way to go if you want to buy a limited slip seperate from a tranny, would be the Quaife unit. Thats somewhere between 800-950. A good way to go as well would be to try and obtain an OEM tranny with an LSD. Thats probably 800-1050, but this price is comparable to the other unit (Quaife) as it has to be installed. Dont try and be cheap on this there are crap LSDs out there that will only cause heartache and pains in the wallet and knuckles. I went with a JDM Y1 equipped with an LSD. I had it looked at when I bought it and have had no problems whatsoever. In looking for these youre gonna have to be careful of what gen engine you have and tranny type to match it to.