transmissions are generally ECU controlled nowadays. Probably, but if so, your ECU will only take a unit with the same gears, ie a 4speed Mazda3 if you have an 06-07 or a 5speed if you have a 08-10, etc. If you try to put an unmatched unit in, you will probably need an ECU tune to get the ECU to read the number of gears, etc, and if you are going through that, might as well pick a good tuner that will increase your hp/torque based on your local temps, elevation, barometric norms, etc. After that, give a mouse a cookie, since you're already on the slippery slope.
