With my superchip I noticed a 2 mpg increase in the city. On the highway though at a steady 70 mph I've noticed a 2 mpg drop.

 

You are the second or third guy with an '03 who can't use the 3815 (Flashpaq) that I've heard say that their interstate mileage dropped. I've not heard that from any of the '04+ flashpaq users. It's sad you can't complain and get an update to help the high speed mileage since yours is not upgradeable without sending it in. I have no idea why the '03 model is so different from the '04+ model...

 

What settings are you using? As far as shift points

 

Well I have the 3714. Right now it has database version 6.02 and if I send it in I can get the latest version 6.06. Superchips tells me that I probably wont notice much difference if any at all. I can't adjust the shift points it's not an option. In the instructions it says that the shift points are already optimized. I wish I knew for sure if the update I can get really would help me or not.

 

Well, I'm not sure how much light I can add on this subject. I have on 04 hemi QC that I just installed 3815 in it before going to Florida with it and I was averaging 15mpg doing 80-85 mph on the interstates with 4 adults and full load of luggage. Now thats not from the overhead console, I assume that was reading higher.Before I installed the 3815, my HWY average was about the same, but lower speeds(65-70mph), so you tell me. I think it helps, it definetly has alot more get up and go!
Also, mine is a Laramire package which is AWD, might be a factor in lower numbers.