Well, for my conversion, I'd need the Corsa VXR manifold anyway. It's pretty much the same bolt pattern as the C16 exhaust manifold, therefore the top row of holes would need to be drilled out to fit the Z18. Yet, funny enough the exhaust ports are in the right place. I've also thought about just taking a stock Z18 exhaust manifold, chop the catalytic converter off and just weld on a flange for a Garrett.