High quality silicone hose, or?
I'd use high quality silcone hose but too much $$$, rubber maybe ok for awhile.
Snorkel in fender, or? What airbox do you have cylinder filter or panel? If it's a cylinder filter (RPO K47) you would be hard pressed to gain much of anything relating to performance or economy, it's a flip of a coin high flow after market filter, or stock filter?
Outside of retro fitting a Douglas air filter canister system effort insulating airbox is worth the effort. I used aluminum faced foam layered around the box to reduce radiant heat. Wrapping downpipe, or ceramic coating further reduces heat in engine bay.
99 GMC SUB, 2500, 4x4, 6.5 TD (F) #H32 enhanced blk, Phaser timing set, B&D IC, 3" ATS exh, K&N w/prefilter, 4WD NVG 246, 4L80E kevlar Transgo off road/tow mods/B&M supercooler, 14 FF MagTec w/locker 3.42:1, 9.25" IFS frt/diff 3.42:1 w/ARB locker, AutoMeter Boost & pre-turbo pyro meter, 12,000 lb hydro winch, Warn classic bumper w/brushguard & diesel scoop, Max E-torq Stage 3, hi pop inj, oil bypass sys, on board air comp for front ARB locker & tire inflation, DynaView driving/auto-cornering lts, DZ nerfs, A/T 285/75/16 SilentArmor 3750 lb rated on 3750 lb rated Alcoa, 3 IP drivers 2 r spares.