I found an article on motoiq.com about a new AEM product called a dyno-shaft.
Its basically a slip yoke with some strain gauge magic and a controller that will replace the one going out of your transmission coupled to the drive shaft.  It will measure torque going to the differential but calculates horse power based on RPM input.
This will be a more accurate and hassel free measurement than accelerometer-based systems such as Dynolicious or G-tech which needs exact vehicle weight and mounting/calibration to give meaningful numbers.
Currently you need a AEM datalogger or EMS to read the AEM-net only data stream and there does not seem to be a yoke/controller that fits on the Mazda transmission.
I like the idea of having tq readings in a datalog along with other parameters like injector duty, IAT etc.
Pricey at $1100 + logger or a compatible EMS.



More info here:

http://www.aemelectronics.com/dyno-shaft-on-vehicle-dyno-73/dyno-shaft-on-vehicle-dyno-sportsman-series-74/