I wanted to get some feedback from all of you who have put kleemann headers on your m271.

I used to get 31-33 highway and 25-27 city before I installed my headers.... now I get 24-27 highway and 19-22 city.

This may be exaggerated because I think I may be driving more aggressively (I've had mine for about 6 months now).... but I did spend a couple of days trying to drive as conservative as possible and I couldn't get anywhere close to the gas mileage I used to.

Have any of you noticed this too?

 

possible....even likely and expected. also, have you gotten a tune on your car since? this may be because your car is running rich and adding in more fuel.....

 

no tune... but i plan to in november

 

its very common for cars to run rich after installing headers. this would result in the decreased gas mileage you are experiencing, though no doubt i would probably "get on it" more too after installing power mods....i usually do lol.

 

yeah i will... but the soonest LET comes to my area is november... so i have to wait

 

Your throttle response is likely improved greatly, hence less mileage.
I can eek out 28 mpg if I baby the throttle (M111) but with pulley, headers, and other things, the car wants to GO. Hard to say no!

 

you could always ship our your ECU and they can tune it and ship it back if you are that desperate lol.....i'd probably wait, but you would only see at most a 5-8 or so whp more different i think (i think, i do not know) on a dyno tune for your car.

 

More power = less mpg.

I'm sure your ecu is throwing in more fuel in since the headers added more power. I'm sure a ecu tune will give you a more balanced a/f ratio but more then likely you'll still get less mpg then stock.

 

yeah... i'm not surprised at the result.... i was just curious if the difference in mpg was similar to others who have headers.

and if anyone have headers plus a tune... i'm curious how much mpg they gained back.

 

psh....31 mpg combined!

 

On my Pontiac that I had a few years ago I installed headers and got about 5 mpg better mileage. On my C230 with the Kleemann headers, I get about 24-30 mpg avereage mileage but I also get a persistant P0240 code which pisses me off.

 

I installed the Kleeman header about 3 months ago. Mileage is down a bit, but not as much as what you are showing. I went from 28-29 or so highway to 26 on a recent 400 mile trip and from ~20 to ~16 city (these are NOT the mileage from the computer, which is good for *****, but manually calculated; the computer is ALWAYS optimistic by 3-5 MPG).

Just FYI, my car is 2004 manual transmission sedan and I drive 85-90 MPH consistently on the highway and drive it pretty hard around town (which is most of my driving).