so i drive a 98 hx, which is supposed to have close to the best gas mileage right?
well with intake header and exhaust I'm getting like less then twenty five miles per gallon, does anyone know what could be causing this decline in Mpg?
I do have an exhaust leak on the downpipe of my header would that be causing it, and is there anything else that could effect it?
thanks

 

Could be a lot of things. Is it cold where you live? Cold weather and winter gas blends will drastically lower your mileage. Mine went from 30 (city) to 26 when the temps dropped consistantly under 20F. Do you drive the car hard? Your not going to get 30+ if your putting your foot through the floor or if you're in stop and go traffic. You could also check the air filter, gas filter, spark plugs, injectors...

 

The exhaust leak is likely interfering with proper functioning of the oxygen sensor and causing the bad gas mileage.