2018 EZGO Express L6 Controller tuning

[GCBearcat]

So I bought an electric Express L6 in October. have read on here that some have been able to tune these things to make them a much better running cart. Mine is disappointing and tops out at only 16mph. My neighborhood has a lot of hills and it won't accelerate going down hill, it seems more powerful going up as strange as that sounds. My dealer has a tuner and set it to go to 25mph but the settings didn't take. He has reached out to EZGO and a couple of other dealers and they told him that nothing can be done. They told him only the first versions of this cart can be tuned. Any suggestions? I have read that Bob Boyce is the foremost authority on these carts and I would love to do something with mine to make it run better. We live in a little town west of Fort Worth Texas.