Type of automatic in your truck?Differences?

Depends, if you own the truck, take it to the dealer and pay them to reprogram it, if you are a company driver, beg, plead, grovel from your employer to get them to reprogram, just understand that they have that feature locked out for a reason, honestly all perf mode does is change shift points, but it can impact fuel mileage

 

On the Mack's, in perf mode, it will start you in first regardless of weight, if you are loaded, it will hit every hole on the way to 12th, if you are empty or bobtail, it will skip gears easier. I always found manual mode preferable to perf mode

 

My current truck has an X15 with a Fuller Advantage. Almost 250k and has never given me any trouble. If I have to drive an auto this is the setup I'd take, although I'll take a 13 speed over anything else.

I've also driven some trucks with ISXs mated to Eaton UltraShift transmissions and never had any trouble with them either.