ahem, in the time that you have owned your car, there isnt any way that you should feel as if you are beyond the potential of an open diff. try to spend your money in other ways.
When you order a diff from the company they ask you whether it is a vlsd housing or open diff housing. There is a small differnce in the diff's so ive heard. but i dont have a 2 way. Look into the different companies, kazz, ats, tomei, cusco. see how they are designed, check the initial lock up torque. Read about their 3 thousand mile fluid change or 1-2 events. Maintence is what is going to keep that thing alive.