I just now noticed this thread and have also bought and installed the zzp shift kit in my grand prix. Since this kit doesn't come with springs I was able to buy new ones from my work to replace the older ones so I kinda coustomed my kit together. I work on large accumulators at my work so the shim idea just doesn't go for 4t65e since we use the same idea as well as the same poly/uhmw material. We use it instead of metal cause its easier on the internals. Not sure if this was zzps theory behind it, but I bought this instead of the transgo kit. No previous problems in my trans but now its just that much better. Would def recommend this kit!
