[Hunner]

Actually no. I did ask about that. That is about 2 1/2 right at the sensor on the stock air box and opens up to 3 1/4 on the short stub that connects to the accordian type stock hose. Mine is a 3 1/2 piece of pipe and slightly less id. I will check that for info. Just the thickness of pipe less. If I understand it right it wants to meter 5% air but Im not sure about how all that computes.
We road tested and everything checked out. Then about an hour later I got the check engine light. They took that one off and made a new one moving the mounting point closer to the engine end. I have been about 100 miles since then and no light. It is a protoype. Im surprised it has worked so well. They wanted to make sure I had enough flex between ridgid mount shield and engine. I think that sacrificed the smooth transiton I wanted. We are not thru yet.
The True Flow design pipe is really a great idea and could be made easily. I think I found a source for the silicone boots. They have some generic black ones where I did all this for $15 each. Without opening the stock box you dont gain more air. That setup would work well if you put on the top for off-road nasty conditions. It still improves performance with the lid on but not as much. I let the air down on my tires off-road so I could easily swap intakes. For casual off-road it would probably be ok either way. I go to a park, SuperLift here in Arkansas on weekends and drive alot so I would like it covered for that.
Any input is appreciated. More experimenting is needed.