I had my 2004 TSX reflashed in August. It is a 6MT and I have also added an Ingen CAI. Here is my issue/concern.
Right after having the re-flash, I notice quite a bit of power and smoothness in the powerband. Zero to 60 was faster and I could get more top end in a set distance.
Now, I don't seem to have as much power as I had before the re-flash. Also, I seem to now have picked up a hesitation when full throttle. It is very slight hesitation, maybe a mili-second, but quite noticable. Even my instructor at the track noticed.
Is is possible that the ECU has reset itself? or, possible a malfunction in the re-flash.
Reflash Issue
The ECU cannot 'forget' the calibration. Check that there are no error codes and go over the engine to make sure everything looks secure. If the throttle response is strange then it may help to pull the throttle body off and clean it. If you do that then the ECU must be reset for the ECU to re-learn the throttle plate position.
Hondata