Can someone tell me the air inlet diameter of the Gen 3. I am making a rodent screen but don't have the car accessible. I'm thinking maybe 3 inches?
Engine air inlet? Assuming yes, I would wait till you have the car accessible. I took that snorkel out to do it properly, cut out and formed a piece of rodent mesh (galvanized steel mesh with 1/4" spacing), with bent-up edges and corner's clipped, drilled 4 small holes through the walls of the inlet, pushed the mesh in, secured with copper wire "twist ties".
I was thinking something like that but externally attached to the very end of the air tube. Maybe circular with four extended tabs bent over the end and attached with a zip tie around the outside. Not as clean but more easily done from a distance. I just need the inlet diameter which I believe is circular. Also, this would keep rodents out of the whole system.
The opening is not round, it is oval shaped. See the picture posted by Mendel. Like Mendel mentioned, your best bet is to remove that plastic inlet and measure it yourself. I think that a zip tie on the outside will not stay in place very well. It would eventually work its way loose, and the screen would fall off. You can still wrap the screen on the outside and drill small holes through the plastic inlet for the zip ties, like Mendel did.
It's a square with generously rounded corners It'll keep them out of the engine air filter box. To keep them out of the cabin you need to remove wipers, linkage and metal cowl. There's an opening into the cabin, roughly 4"x10" IIRC. The same rodent mesh, secured with sheet metal screws, works there. There's also two exit vents under the hatch floor, in the corners. I ended up removing the rear fairing, making little rodent mesh "boxes", secured to the plastic surround to the vents with sheet metal screws. To stop mice? Should be. Also, you don't want to impede air flow any more than necessary.