Air filter: Try the K&N or Amsoil that fits in the factory enclosure.

Oil/ Grease: Synthetics should be fine. The sooner the better. Engine, transmission, transfer case/tod, differentials, wheel bearings and u-joints.

Exhaust: PV. The PV 1st.gen. catback system(stainless) had a smaller diameter tailpipe tip than the stock VX tip. You may be able to change out the tailpipe tip to custom tailor the sound to your liking. Some members were checking into custom silencing tips, but never heard any results. Maybe THEY mellowed to the muffler's sound.

Gas: Regular grade should be fine, until you install a supercharger.

The only rack that will fit must be purchased through the dealer. Folks here like St. Charles Isuzu's prices.

Lastly, forgive my heretical sacreligious blaspheming, but don't use power mode and keep your foot out of the gas for the best mileage

Disclaimer: Your actual mileage/results may vary.