Has anyone done this? Will dealerships even concede to this? Would I notice any differance in performance/cold start/throttle response? I've got an 03' with a Promini/BMP intake, 15%, and Borla race setup BTW.
I've lost track as to what ECU version I'm at now, but like most for the past few months I've been suffering from frequent cold start issues and horrible throttle response. I've talked to MINI of Peabody and supposedly they've got new-ish software. I'm entertaining the thought of having them flash the JCW map instead. They haven't gotten back to me as to whether they'll do it or not. Another suggestion from MOP was to "run a tank of lower grade of gas". This sounds familiar, and also not something I'm eager to try.
I'm aware of the other after market ECU options that exist, I'm just trying to get feedback on this particular option.

Thanks in advance for any input.

 

Officially, a dealership CANNOT do this.
The cars VIN specifies the allowed software for the car so only if your car has previously been updated with the JCW kit, will the JCW software be offered for it.

I've seen many people say good things about MTH; since you have aftermarket parts already, going for the MTH upgrade might be the better option.
There is someone (Lee Malo), an ex MoP tech, in Gloucester that has the MTH upgrade cable and MINI experience ...

Web search:
advanced technologies / lee malo / 27 kondelin rd / 01930

 

Before installing an A'PEXi AFC2, I considered the JCW map. I spoke with the MINI shop about installing the JCW upgrade kit with JCW injectors. So long as they were installing the upgrade kit, they were willing to flash the JCW map.

I decided on a more custom tune to my mods, and I'm very pleased. But the JCW bits might still be a good play.

Let us know what you learn.