Sorry I wasn’t clear but yes I put the JDM S14 wheel on my USDM S14 (that’s my car in the sig). I didn’t get any trouble codes or errors concerning the SRS airbag system so you probably don’t need to worry about that. (the JDM S14 wheel uses the SRS system). The JDM S14 airbag wiring plugs right up to the stock US wiring. I don’t know anyone personally who has put an S15 wheel on an S14 but I found some threads on Zilvia about the install. It sounds just like the JDM S14 wheel install, it’s basically plug and play with the airbag wires and the horn wires...
http://www.zilvia.net/f/showth...n+S14
and another thread...
http://www.zilvia.net/f/showth...n+S14
I hope that helps answer your concerns and questions...
Some notes about my install…I have a small gap between the steering wheel and steering column cover but it not a big deal in my opinion and for some reason when you take off the S14 wheel and put it back or any wheel back on for that matter it clicks when you turn the wheel. Again it’s really not a big deal because its such a quite click, you can only hear it when the car is off. I think they discuss a solution in the second link. You said you have swapped wheels before so Im sure you already know this but I cant stress enough to make sure the battery terminals are disconnected from the car before you start to take off the airbag and when you re-connect the new one... and be careful when you start the car for the first time... I have heard that airbags can be screwy when you disconnect and reconnect them. I have never heard of something happening but its better to be safe than sorry. Good luck with the install if you decide to do it, let us know how it goes...