I have a 2000 Expy Sport with a 4.6 and 331 rear end. I have a open K&N filter and no other mods. Which is the best chip and what gains and gas mileage improvements will I see if any. Do I need to run a higher octane gas with any of the chips? Can I still use the 87. Thanks for your help.

 

The Diablo, primarily because the Superchips has clearance problems in the Explorer/Ranger. Well, yes, we can program an 87 octane chip but you'll get only a firmer ship and no horsepower gain. Ain't no free lunch! Gas mileage may be better but there is no guarantee. Normal driving you should get better mileage but a chip will decrease it if you get into the throttle too much (it burns richer at WOT).