Winchester, Invector, Mossy- Kicks GT 665 vs. 660

[Rockhound]

I was wandering if any of you guys had tested the difference from these two chokes. I have a Kicks GT 660 and it slings some good patterns at 40 yards with lead and htl, But i was in an old store yesterday and found a Kicks GT 665 priced really well. Since i have 3 guns that use this thread system i thought i might go back and pick it up. My quesion is How much difference in patterns will it be from 660 to 665?