[///M1]

Originally Posted by Franklin Joseph

I've dynoed my car a few times, both mustang and dynojet, both stock and with mods, and everytime i'd ask the operator to dyno with and without the M button...everytime the difference was within 1-2hp.

10psi is way too low.

+1. Here is what I posted in the other thread, which confirms your findings:

1. I have dynoed the car with M button on, and with it off (in consecutive runs). No change in observed peak HP numbers.
2. I have a boost gauge (get's physical readings through DV lines as opposed to the CANbus version). No observed difference in peak boost between M and non-M mode (15psi peak on stock tune regardless if M button is engaged).
3. I have also logged the car in multiple parameters, peak included, through the AccessPort. Again no difference in peak boost was noticed whether M button was activated or not (via ECU readings this time).
4. Tuners like COBB have maps which disable the M button all-together (e.g. their 91 and 93 Linear Throttle maps where there is no difference if you depress the M button or not). This results in no change in recorded peak power as compared to there Non-Linear Throttle maps (where the M button is allowed to work). All it changes is sensitivity on throttle response, not peak power (nor boost).