chevy0128

do headers make u run a tiny bit lean or rich?..or neither

black01_WS6

iTrader: (13)

it makes it run lean, but the computer will compensate and actually run rich.

167camaro

iTrader: (5)

That has been my experience also.

CAMAROZ28AQUINO

rich, but nothing major

chevy0128

so it wil be kool to drive without it tuned for a month or two?

SOMbitch

iTrader: (8)

Your gas mileage will suck!!!!...... worse.

ChocoTaco369

Both.

Headers make you run rich down low, which is why people's mileage goes down when running untuned after a header install.

Headers make you run lean at WOT. It's not particularly good for the motor to go WOT without getting your A/F ratio tuned after a header install. Unlike a cam, you don't run the risk of quickly destroying your motor by not getting it tuned, but it can shorten the lifespan of your motor in the long run if you never get it tuned if you love to go WOT all the time.