Does the boost bypass just drop the boost a little at the 1-2 shift or does it drop it to 0? I noticed tonight that when my L shifts from 1-2 I lose about 4lbs of boost, but it comes right back. I bought the truck used so I don't know if it has the boost bypass mod or not. I figure that it is either that I need to do the boost bypass or belt slippage due to the smaller upper. Any help appreciated.

 

Is your truck chipped or stock?

With stock programming, like mine, the truck runs on 4 cylinders during the shift to save the transmission. This is called "torque reduction."

 

I guess that would explain it - it is stock