yes they are stock

 

do you have any other chip or anything that you put on, the tuner should take care of it,sounds like it is not saving.When i had my gears changed i was off by 12mph, got a tuner and that fixed it.I then got a vortech and had to use the chip they gave me for a while and that chip over ride everything on the tuner.I think its something with your tuner and saving your setting, and if you put a lower gear in there its going to sho faster, maybe try 3.90 if it wont save the 3.73 and you should be close, one other thing is the rim size, check that to make sure its on the right setting.

 

i dont have chips, i tried the 3.26 and 3.73 and both of them are the same result

 

Sounds like it could be an issue with the tuner man, where did you get it from? A buddy of mine had a similar problem with his predator, he sent it back to summit and they sent him a brand new one free of charge.