can you here a differnt sound from the motor (advanced timing or something) when it comes on, i can sure here a different sound, i also installed a light which comes on when the pump is running, check out what boost pressure it comes on at, mine is around 18lbs of boost

 

The sound changes a little bit, mine is quieter. Mine is set to start at 20 and max out at 30 psi. I can definitely feel it. It's not a huge jump in power like pushing a nitrous button, it's controllable with the accelerator, I can hold 25 or 30 psi while accelerating, or I can floor it and let it do its thing. I'm running the Snow Performance setup with the progressive controller, I really like it because once you get the system tuned right it's transparent - you just hop in and drive like normal. The truck doesn't take off like a rocket when you hit a certain level of boost, the power just builds like a normal high performance diesel. You don't really notice the system unless you turn it off - I like that. I didn't bother with the indicator light because I figured I'd be able to tell when the system kicks in.