on this topic. I went from the open air K&N air filter. Cleaned every oil change and swithched back to the stock airbox just last week. I have gained so far 80 miles to the gallon per tank. THat took me from 14.3 miles to the gallon to 16.9. the only other change that i made to the truck was switching off of a full synthetic oil. I was pissing money away just burning the mobile one oil. Will be doing a fluxh change this week after the rain stops to make sure I got all the synthetic oil out.

I dont think that the isuzu product engines were made for the open airfilter like K&N. Just my 2 cents though