I unscrewed one side of the voltage regulator and rotated it down. This left a big enough flat space for a 5 or 6" hole with the cone shaped flashing behind it.
The hard part was fabbing up a flat space to clamp the ducting to the funnel. I cut a strap 1" wide off the side of the flat metal, held the end of the duct over the narrow end of the funnel and traced around the end of the duct with a dri-mark. I cut slots from the edge down to the line and bent them up as tabs. Then I made a hoop out of the rectangular strap just smaller than the inside diameter of the duct. I pressed this over the tabs at the outlet and pop riveted the collar to the the tabs. Finally I cut all the tabs off square to the collar and clamped the duct from the stock 6 snorkle to my ram collector.
Do all the fabbing, cutting and pop riveting before you mount the thing on the radiator wall.
Zoom, zoom.