Stainless steel snorkel

[Hillbilly Heaven]

Carbon fiber tube is outrageous in price! Not building telescopes or rockets
Fiberglass tube might be a good option, depending on price, using silicone couplets and elbows. It needs UV protection.
Thin wall stainless or aluminum tube is most cost effective. A high quality top shelf exhaust shops can bend and weld stainless for you. If they stick weld joints RUN AWAY. They are using mild steel welding rod and joints will rust. Aluminum is lighter but does take more skill to weld properly. Neither need special treatment after construction.
PVC is too brittle and structurally sensitive at extreme cold temperatures. Sensitive to UV unless coated

Donaldson makes great products but be warned that average sized products are airflow CFM limited. Too get the CFM you and I need puts us using the larger size pre-filters. They end up being giant limb catchers.

 

[Alloy]

Aluminum would not need anodized, assuming you don't use some corrosion prone alloy. Plenty of factory cast aluminum intakes and heads without anodizing. AL forms a protective Aluminum oxide layer within seconds of exposure to air.

I've worked with aluminum for many years. Aluminum Oxide is similar to Iron (rust) Oxide on steel. Once either oxide builds up it comes off.