I would say, you have selected both the old and new version of NissanGTR, 1.0 & 1.1. Just pick 1.1. I'm not even sure how you have 1.0 in the list? (maybe you have files installed in your core folder?) Nothing to do with your error message, unless you untick all the boxes on the left you will end up with an 188 Meg monster mod too. You don't really need anything in the bottom box like talent files, Sound etc.
Thanks very much guys -- managed to get the mod to build on my main machine and transferred it to my laptop to host the race. There should be a server up called C3PO GT1 Server -- feel free to drop in!