Check Amazon. I found a 3.5" 180 degree aluminum long radius and 3.5" straight pipe there.Gotcha that piece of pipe in the box looked like 4”. I’ve been looking around online for little sections of 3.5 and filter / v stack combos to make my own short ram and cold air when the time comes. But it sounds like what you’re making is going to be way cooler lol.
Summit Racing is my go to a lot.