OK.
I presume my 1997 is also a GEMS - as far as I understand the A&R box allows the ECU to work as normal on petrol, and then when it switches to lpg it still works as normal but adds whatever degree of advance to each spark you have set the box to. Whatever ever happens, it runs brilliantly on lpg with the box, much better than prior to fitting so it's worth it to me. :)