Originally Posted by PAO56
will all the talk of headers and exhaust....i would like to know what impact if any it has on your gas mileage....supposedly the new Impreza is tuned to optimize it for MPGs.....not sure there is much room if any for pure performance upgrades on this one.......will be curious to see what the true tuners do with this car....and the impact on MPGs overall....
Any time you deviate from an OEM setup, things will change. It's inevitable. As far as headers go, the UEL headers from Rallisport Racing may or may not have an effect on MPG. This would not be a modification intended to increase performance. Swapping out EL headers for UEL headers would solely be to have the boxer rumble. If anything you would probably notice a slight decrease in performance since EL headers tend to smooth out the exhaust flow. As far as the rest of the exhaust goes just swapping out the muffler should not produce negative effects on MPG. Driving around today, I did not notice a decrease in the MPG's. But then again, I will need more driving time to say for sure.
For the intake, I have plans for modifying that as well but not in the sense of adding a cold air setup. I have a couple of ideas that I am tossing around and not sure which one I want to go with yet. I spoke with the guys at EFI Logics a while back and they told me that it's not worth while to change it, especially since the car cannot be tuned at this time.
The Impreza was not intended as a performance car but that does not mean that simple bolt on improvements here and there wont' net a slight increase in performance at the cost of a few MPG's. That's worth it to me.