I'm going to buy them this week and see how they do on my 3.9. I always average 17.5mpg so if it goes up then they work I hope lol.

 

It does not make a lot, I make on average 15L / 100km and if my calculations are just it makes 15.53 MPG for V6 3.9L (45000 Miles)year 2002

 

ya i got a hell of a deal on mine only cause the one under this were messed up in invetory so i got these like at half price and its not a huge noticable diffrence and dont really thing there worth the money but spend it how you want but the one good thing is that they do not need to be gapped ever!!!!
and thats in my 4.7l

 

in all honesty, you're better off just getting a decent plug like an NGK or autolite 3923. They're not worth the money. If you really want mileage, you'd be better off geting a superchips and using the mileage tune. My 3.9 usually averages around 17mpg mixed, strait highway it can get about 22 mpg so your mileage is pretty normal for a 3.9. I just got a good job so im planning on getting a new superchips when I start getting good paychecks.

 

I can't wait to try a chip. I know our trucks are way under powered but I am going to make the most of it till it falls apart.