I am trying to find the cheapest tuner for a 3.9 but it has to have the option to adjust tire settings. I put new e3 plugs, muffler and intake and truck seems better but now I want to tune it for the intake and exhaust. But I can't see paying over 300.00 for something I might just use once.

 

Superchips helps the 3.9 a ton. Even though its $300 it has multiple settings and uses. You can tune it for higher octane and really improves the trucks power and torque. You can also recal. the speedo for different tire sizes like you want to. Also you can choice different tunes at any time. So although they are expensize they are worth it.

Also try ebay. You can sometime find some good deals on there. As long as it isn't vin locked. Or even get the previous model, the 3715 for around $200. Does the same thing only you can not update it online...

 

Thanks for the help. Gonna get one soon as I can.

 

with mine when i set the tire setting to 31x10.50's my speedo is off...i found like 29.75 is about on unless i'm going over 75

 

right now my speed is off by about 10%....So i just keep in mind that i'm doing 110%of what the speed says. 35 = 38.5, 45 = 49.5, 60 = 66, 75 = 82.5

 

Why is your speedo off so much? Did you change the tire size?

 

yes...265/70-16