What dyno are you using to fit the 143" wheelbase and AWD?

 

We have a Dynojet 424xLC2 with the 10" extension

 

so the 1 7/8 were not tuned for? or were they tuned for?

 

You believe the 1/8" larger primary changes the tune that drastic that the info I provided is not accurate?

 

so how much more power do the smaller headers make below 3500? My sceen is too small

 

The 1.875" headers make more power down low. Then they seem too equal out up top

 

AGAIN, bigger is not always better. Thanks for sharing the results. Big tubes tend to sway towards BIG cubes and FI. On a stock ci set up with bolt ons, the big primary set up is not always best.

 

I'll post Dyno graphs of y truck. I went from stock manifolds to the ARH 1 7/8 hense the test above was done. My truck responded the same way and I have a TVS1900 on it. It hardly changed the AFR. I'll get my graphs up to show the difference. The stock manifolds flow quite well

 

yeah, I have seen it. It will go rich explaning the mid range boost, and the same results on the top end. Get the tune right for the new headers, and go see what it does. I would be willing to bet it helps a lot up top.