Changing gears is probably going to effect the speedo more than the tire change (going from 4.10 to 4.88). If I've done my calcs right, the combo of 33's + 4.88's should result in the speedo being low by about 5 mph. Do you think the dealer could fix this with the program? Or do you think the better bet is to use one of the aftermarket devices you suggest.
I was going to go with the FlashPaq, that claims to be able to handle this and there are at least a few wesites saying its CARB approved, but when I checked the CARB EO's, the unit that supports the Jeep 4.0 isn't listed (its supposed to be EO D-330-9). It figures