I was after the same answer Roy. I want to put a HKS 3037s (when i find one, which may end up being new) on a low mount setup on my RB31DET in my R32.
Ive been told numerous times "All Jap manifolds are highmount, you have to get a custom one made up" So i emailed GCG. Nope - dont do it.
Have to find someone willing to do it, which could end up in a manifold that wouldn 't produce desired results.