Glad things are working out for you. Probably the one thing contributing to tighter groups is that the arrow spine is a closer match for the rest of the set up.

One other bit of advice. If you are serious about archery then over time learn all you can. Learn to work on your own bow including the important measurements to record for reference, bow tuning replacing rigging (string and cables) and maybe even doing complete tear downs and putting the bow back together. Someday you may feel that you've become the best bow technician you know. Saves a lot of gas and guessing who knows what.