First check that the TSB on the transmission was done! That’s a huge improvement. I have a early 17 Pro and had to have the TSB done. Also when it gets around 15K mikes it will run much better. Mine was sucky at first too, 20,000 mikes and I love it!
Please wait until you get 15K plus miles. Yep mine was not great until about 15K. Have 20K now and it's like a completely different vehicle. Takes a while to loosen up I guess!
Look at the 275/70/16 KO2's. They are 1.8% bigger and are C rated. That's 1.8 mph off at 100 mph. Basically nothing. I think that's what I'm going with soon!