The flex tubing was at Lowes, or Home Depot. Can't remember which, but it's 4" diameter vent tubing. You'll find it in the roofing section where you will also find the 6" to 4" metal adapter. There is also a 6" metallic enclosure that would probably be a better choice than PVC. I really had to work with that PVC, and a dremel to get it to fit correctly both in the engine bay, and over the filters.

Keep in mind that none of this was plug and play. I did a lot of cutting, grinding, etc... Your intake design is good, except for how you're using those rubber couplers! (use metal pipe section), and if you can build a sealed enclosure up front that might work out better from a IAT standpoint. There's a lot of heat where I have placed the filters, but good shielding should prevent any heat transfer. Return those filters, and get the ones I got with open end. Definitely better flow.

okay ill get on that but i dont know how i could build an enclosure for them, any ideas?

My main tool for most custom projects is a dremel...

All a real man needs is a leatherman.