So first off, the GTO Monaro. Been doing a lot of work for this car for about 4 months now, it was a pretty major project. Basically I needed to make the airbox and intake plenums for the car, as they had a custom LS7 inlet manifold made by Harrop but Harrop couldn't supply any of the support gear. So here is what I came up with:

However we since decided that this had design issues, and could be done better. So I made version 2, featuring recessed bolts, a more compact design, and a v-weave finish:

Brian, you're correct, the plenum was infused in one piece. I'll try to get some photos of the mould for you. Basically they were 4 part moulds, and I laid each of them up individually and trimmed the carbon flush with the split lines prior to bolting the pieces together. Then laid strips of carbon over the joins and then the usual consumables. It's tricky to do but the results make it worth it.