Thanks Tony. I'm not too knowledgable on the Skylines, but I think the cars pictured above are pre-R31 (R30?). These are the turbo 4 cylinder models that raced in 1986 and '87. Then in '88 the turbo 6 R31 arrived. As a race car, these were fantastic just for the noise they made, a real high pitched shreak, as opposed to the dull flat sound of the earlier 4 cylinder versions. There are a couple of R31s that have been racing with historic Group A for some years, and they sound just as good as I remember.