Your car did have an STI8 wheel fitted for a while (same as mine, now Tim's). My airbag light went out fine because it's a later UK model. They took the steering wheel off cos they could not get the light to go out. I understand the wiring is different? Stuart from EastSussexMobile will be able to advise. He fitted mine/Tim's.
Sorry Tim! In a time warp for this enquiry. (I have changed my avatar though!!)
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Toyobaru 86 with Cosworth exhaust brakes and supercharger, Cosworth mapping, Eibach lowering springs, OZ alloys, fast road geo and various cosmetics. Great fun!