Many of us in this group never saw a JL in the wild as we waited and our projected build dates came and went for our 2018 JL's. Even getting told it was ready to ship from the FCA hotline only to find it was not so.
Very unlikely the delete caused any changes. As for the downshifting you just notice it because you can hear it. I think it sounds great and have had nothing but compliments about it. I am running 35's and average 20 plus mpg in the summer. Very happy with the Dynomax delete pipe.