hey guys i just got my xcal2 last week, i have already tried 97 tow and 91 perf. i want it to shift a little firmer when i am on the gas but before i change it i want to make sure that it wont hurt my tranny at all. by the way i have an 02' scab with the 4.6 and oversize tires and the tuning definetly helped, it feels like it did before except it revs quite a bit faster and when i look down i am going 5-10 mph faster than i think i am. i am pretty happy with it although i thought i might gain a little more thatn i did, but overall i am pretty happy with it.

 

It shouldn't hurt your tranny by upping the shift firmness..