On my 99 SS, No mods other than a D1-SC with standard ati crank pulley and 4.10 blower pulley... My gauge reads about 4.5-5psi at 5,000 rpm, is that about right?

 

Sounds about right, I used a 3.85 on my old setup and got about 8lbs.

 

So weird because I have a 4.75 pulley and get to 10lbs...

 

Is this the six rib set-up? If it is, you are where you should be at only 5000 rpm. I use to make 7 psi at 6000 rpm with a 4.00" pulley with the six rib with headers and exhaust. Make sure the blower belt is tight, you shouldn't be able to flex it. Bob

 

I would check the belt, I had a customers Z06 on the dyno a while back with the same problem, tightend the belt picked up a ton of power and 2-3 psi.

 

The belt is pretty tight, can be plucked like a guitar string... has anyone ever noted the torque they applied to the tensioner bolt?? Also, yes it is a 6 rib set up.

It could be an error with the gauge with the tiny 1/8" plastic hose ran thru a few bends to get to the interior too I suppose.