header gas mileage?

[lifted4.0]

for all of those out there that have put aftermarket headers on their ranger, preferably a 4.0..is there any noticable mileage gain? loss?

i have a 2003 ranger 4.0, i havent looked for the EGR valve yet (if its there) but if someone knows of the top of their head if i need EGR and what side its on, that would help alittle,

THANKS