I installed a Magnaflow dual exhaust along with a Diablo Sport Predator programer (performance tune), MPG increased 2.4 MPG, I installed a K&N CIA (off road) and MPG went back to 12.5 on hiway @ 70 MPH, 13.5 @ 65 MPH....... Any ideas???

I spent over $1,000 did not realize any increase in MPG, therewas in increase in performance..... Note, my wife was driving andshe IS NOT an agressive driver.....

In addition, will converting to JBA headers increase MPG.....

 

As you add more air, your computer will automatically add more fuel to maintain a given a/f (air fuel) ratio. When you added exhaust, you didnt add more air coming INTO the engine so it went up because it had more free flow out.

 

The K&N CAI may have changed the MAF table, if that's the case, about the only way you can fix it is with EFILive and a flowbench.

 

2.4 mpg increase! Thats pretty good for an exhaust and performance tune. I may have to consider doing that. Where is the Performance Tune available from? is it just plug and play?

 

I got about a 2.8 increase after I did my Volant CAI and Magnaflow Exhaust!!

 

so you guys are going from 12s mpg to 15s mpg?

 

10.1 to 12.9

 

You can increase your MPG by 1 if you remove the screen between your maff and your filter. Only GM uses them, and I dont know why. All i know it to do is restrict the air flow. I havent had any problems withmy H2 since I removed it. Did the same to an '07 Tahoe that I sold and never had any problems. It might add a little power, but its minimal, so you probably wont feel anything. Not sure if the earlier models hae them either. Hope it helps.