The RZ is the older one, those tube's where big back in the early 90's but faded cause it really didn't make that big of a diffrence. The RZ was like what the V-spec is now But earlier. The RG of course is the older sibling to the VG. For club racing use the RG, it's dependable and will stay true.A good work horse i guess you could say. The V-spec is awsome! Great power and smooth. Use the Vg if the track is loose and small.(somthing the V-Spec would be too powerfull for.) Hope this help's. Carl.