I've used the inserts in a fwd for 8yrs with no problems. My car did mostly spin both wheels in a strait line but I wanted to make sure as I frequent Shannonville. With the insert even cornering under power was different as the car wanted to push to the outside instead of one-wheel-peel. The original insert was replaced 2yrs ago when a shift fork broke, mostly as I felt the springs had lost some tension as it may have been used when installed. It was replaced with RTM's version and it works as advertised.