A few posts ago I had a critter chew many wires and my computer had to be replaced..since then my mileage dropped at least 4 to 5 mpg if not more..I've had the magnum about 18 months. I was averageing 23 hwy with a/c on and 20 all around average..I put a CAI and cat back exhaust and picked up 3 more mpg..I was impressed..When the computer was installed I questioned the dealer and asked them if the new computer will "think" my car was new..He said he will flash it and it shouldn't affect it..Car runs good and sounds throatier..A guy I know said there is a chip inbedded for break in and it will run a little retarded for a while..I v'e gone 400 miles so far and I wonder how many miles before the computer sorts out the mods and kicks in for better mpg..The dealer said give it few tanks of gas but my friend said it wil take longer..The exhaust note is alot deeper..I've had the catback for 6 months or so. I can hear the difference so I believe my friend and hope it is temporary.16,500 miles so far..any Thoughts on this subject?????Thanks

 

Maybe you need to put more miles on your Magnum than 400 to relearn driving habits. Unless the dealer was able to "save" the memory from the old chip, I would think (and I am certainly not an auto mechanic or electronics whiz by any far stretch of the imagination!) you need to go thru a break in period, IMHO.