Slight vibration in reverse after topswap?

[natethegreat]

Well, just did a top swap on an 02 grand prix, and now whenever i put it in reverse it vibrates a little. Almost like im slowly letting off the brakes and theres that little vibration. Its not real pronounced but i can still feel it. Any thoughts on what this is? Could it be related to the top swap at all? Right now i have a tune with gtp trans settings, or at least thats what i believe. Thanks!

[nos4blood70]

Did you account for the different gearing in the tune? :O