Check out this guide on ICDO
Cat Velocity Tuning Guide
I think my mainspring tension screw on my Cats are turned in 3 revolutions, my velocity screw unscrewed 3-4 revolutions and my recock unscrewed probably about 3/4 to 1 revolutions.
I use HP air and prefer my Crossfire steely tank which delivers 850psi consistently.
My mech ICD markers will pound down (go pppppp) when I am not shooting paint. This makes for a very efficient marker, but prevents the bolt from recocking when dry firing.
Print out the guide, take it to a field, find a chrono, put paint in it and go from there.