LSD noob! Help me out!

[ksharp]

So today I just picked up a S13 coupe. The seller tells me he put a Nismo 1.5 way LSD in recently. Now I've never driven a car with an aftermarket LSD before but it seems to lock up really well, almost too well. I notice the tires chirp on low speed, tight turns. I've seen people run welded diffs before and it is similar to that kind of behavior. Now I had a good amount of time to talk to the seller today as we had to wait to get the smog done before I bought the car and he came off as a trustworthy guy that was really open to any questions I had. He told me that he bought the LSD off craiglist and put it in himself. He didnt mention what type of Nismo LSD it was besides it was 1.5 way. I have no reason to believe he lied to me about putting a Nismo LSD in there but I've never really heard of LSD's locking this hard similar to a welded diff. I guess my question is, is this type of behavior normal?