at 150* i would wonder if there was even a thermostat installed?

I'm currently gathering parts to change over to an E-Fan setup to gain those few extra MPG's... I'd better not be getting less

better track your gas mileage good to see if there is a difference. i know i was using my fuelly's account before my gas mileage took a big dump.

The fact that I was recording 14.5 mpg's in my red 3/4 ton says something. Seems like a lot of people think anything better than 12 with their stock ram is impossible, but somehow with 35's and 3.55 gears (all kinds of wrong), a stock motor with E-fans and a double roller timing chain I was managing 14.5. I'm sure the NV4500 helps, but I bet with the right gears or smaller tires it would have been even better.

I've been using a Gas Log app on my phone for years, so I have a pretty good feel for how my mileage is on average.

That's how I know I got 1.25mpg by changing to the K&N CAI.

It is also why I'm only making incremental changes (single mods at a time) and not changing out a whole heap of stuff at once... this way I can see what has really helped.
I know certain changes will have even greater effect when combined with other mods, and I wont really know which was the biggest contributing factor, but at least I'll have some idea.

I would be interested to see what the difference between the K&N cold air setup, and JUST changing to a high flow filter would be.......

I'd be interested in that info also... I would think it is solely the high flow element that is key... if you think about it, the K&N intake tube is of smaller cross section and longer length than the standard intake, so that isn't helping, and the air temp at point of draw is questionably of little difference... so the only thing left that could be the major contributor is the resistance of the element.

i have a 2001 ram sport 5.9L 4X4. Went up one tire size from stock and have a k&n air filter, flowmasters and no cat. Im geting 14 mpg city with a bad plenum gasket. Soon to fix that and get e-fans. i hope u get to the bottom of this so i dont lose mpg too!

Since your odometer is off due to increased tire size, I question ones ability to get 14 mpg with blown plenum.

i would be testing some electric fans in my ramcharger already if the newer magnum clutch fans were not such a pain it the @$S to remove. need to get a stupidly large wrench and a specialty tool to break it free.