Couple of problems with the stock ECU (there may be more):
1.) Immobilizer, you will need some kind of work-around for Honda's built in immobilizer.
2.) Drive by wire ... one of the main reasons to go KPro on other electronic throttle body setups is to bypass the stock ECU's drive by wire setup. There is no real work-around for this that I have found, either you have to convert the gas pedal to electronic, or use a different engine management system.
The go-to Honda guys in my area (Speedfactory) have suggested that I go with the AEM EMS system to manage this engine. It will cost a little more than KPro and isn't as easy to setup and use, but because it is fully customizable it can be made to work with the throttle setup I want and the different style of sensor that the z3 uses.
I have also been in contact with KTuner about this and they said that with an OBD breakout, immobilizer work-around and a swap to the electronic throttle system their flash for the 09+ TSX can be made to work for a swap, but that's not it's intent.
At this point I'm leaning heavily toward the AEM unit as my solution.
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