For some reason after my nismo headers and exhaust went on I've increased my highway cruising MPG from 22 or so at 70 MPH cruise to 25-26 on 70MPH cruise.

Has anyone else experienced the same effects?

 

I'm putting on my HKS in a few weeks, I'm hoping to get some increased MPG too. I have no idea why, but I've frequently heard our cars getting better MPG after some simple bolt on mods.

 

Of course your MPG is gonna go up :P Just because it adds Hp doesnt mean it will have a negative effect on your MPG When it comes your engine and letting it breathe more its always going to get more miles to the gallon....engines need to breathe ~_^ thats my 2 cents

 

^ I agree except not if your foot gets heavier with the mods

 

yeah a good intake and exhaust will def increase your MPG. I didin't know Headers inpoved it as well. To my knowledge i believe the only N/A engine mod that decreases MPG is a plenum spacer and/or bigger plenum. And someone chime in if I am wrong but that is what I was told.

 

A plenum spacer should have almost no negative impact on fuel economy.. or it might possibly increase it a tad(unlikely to be noticeable though) if some cylinders are not getting sufficient airflow. Unless your spacer is like a 5 inch spacer, you won't see any losses from it... I know I didn't.

 

Sounds like a pretty big gain for the mods you mention. However you're starting from a low base of 22. 24.9-26 is my normal highway fuel economy without headers and OE exhaust.

 

my current drivetrain mods are non-revup lower plenum, MD 5/16" spacer w/ CCV, k&n drop-in filter, OE z-tube, nismo headers, nismo exhaust.

 

thanks for those who chimed in about not losing MPG. I obivously understand that fact and did not expect negative impacts to MPG but for such a drastic positive impact I'm very surprised.

 

Your gain will be lost as soon as your brain gets used to the enjoyment of the fun pedal. I noticed better mileage when I put on headers and exhaust, but only for the first tank. I liked the sound so much I couldn't keep my foot off the gas.

 

Haha! This post is great :P I plan on getting Stillen Headers, Test pipes and Stillen Exhaust. I like the nice low revin deep tone it puts out. Hopefuly, if im lucky, its gonna increase my MPG too ....but like he said....only for the first tank ~_^ Although you have to give a thumbs up to Infiniti for puting such a nice sound stock exhaust on it.....what are some other positive increaser to MPG beside exhaust components? I travel on the interstate alot and i must say, the highway MPG deeply depresses me :/ Think i need to get a K&N or would an Injen CAI increase it more?? Not sure where CAI stands as far as fuel economy. But what other stuff helps besides helping your engine breathe????

 

I have a set of Stillen headers in my garage... waiting for someone like you...

Don't underestimate the value of breathing. I went to AEM intake, headers, high flow CATs and Stillen dual exhaust. That sure woke up the sleeping dragon within the engine. Well worth the $ IMHO.

 

The way I look at it, mpg should go down with any intake mods, and improve with any exhaust mods ...
more air -> ecu compensates by throwing more fuel in -> more power and less mpg
exhaust decreases losses due to "exhausting" and fighting back pressure = better mpg

just my $.02

 

colder air might be part of ur increased MPG.