and how do you turn it up? is there any negatives about doing this? gonna ruin anything? thanks

 

I believe that is a performance mod that can be done on a first gen dodge cummins with the VE rotary pump. With a 2001 your only option is electronics.

 

The screw is for pre 24V trucks. A box or sticks or both would be the direction to turn. Mild sticks with a mild box puts you over 300 ponies and very towable. Of course gauges are recommended before doing any mods. Intake and exhaust improvements help keep EGT's in check.