what gavin said. and also, the japanese and aftermarket mustang saddles are not wide enough to make a contact with eachother, like the jaguar saddles. so they slide about.
alot of people complain that they knock the strings off jaguar grooves. and that mustang saddle grooves are much deeper. but in actual fact, the difference is only very slight. and i'd say that if you can knock a string off a jaguar groove, you can also knock it off a mustang groove as well