Alright, I am changing my clutch to an ACT street/strip clutch, and I learned last winter that my Posi wasn't really working... Since I am going to be replacing the LSD now, should I just get a used one from somebody here/ebay or should I get a new aftermarket unit from rx7.com or something? Basically, how solid is the stock diff? Mods are in my sig.

 

I think the best options are one of the following:

1) Buy a used low milage FD torsen LSD. They are pretty good, handle a decent amount of power (how much HP are you planning putting down?) and have a fast lockup, and are quiet.

2) Rebuild your stock LSD. Mazdatrix sells rebuild kits for the stock clutch LSD, and you can even rebuild it with higher performance discs.
http://www.mazdatrix.com/g8.htm

Or you could go spending an insane amount of money on an aftermarket LSD (KAAZ maybe?) but I dont think its worth it for a street car. The stock T2 diff can handle a good amount of power. Ive seen people running deep in the 11s using the stock rear end, with no problems.

 

How hard is it to rebuild a diff?