Hello Alpha5811. Not sure I can be of much help. I did install the Devil horns (which look more like Buffalo horns when installed), and I connected them to tubes I got from TVT. These were the correct width of 3", and used rubber connector
to attach the Devil Horns. The rubber connectors are what passes through the radiator support. The passenger side is
wide open, whil the driver's side is a little constricted by the radiator sholder and the smaller hole in the support structure.
However, though deformed a bit, the rubber connector conforms to the space nicely, with no bunching. Good luck with
your project.