I can't help with your question but If you want to avoid the header because of cutting a hole in the cowl this is what I found.
I am building 2 Cuda's at the moment. For mine I had the engine and header purchased early in the build and with the header I got from DA I did neet to cut a small hole in the side of the cowl BUT the header for the other Cuda was purchased back in June and it looks like they tightened the radius on the header so it now fits neatly inside the cowl with no cutting needed.
just a little FYI

Steve