Finally got around to getting the numbers for you. <img src="/forums/images/graemlins/shiner.gif" alt="" />

The numbers are from the service manual for my '94 Montero.
Displacement is .59 cubic inches/rev. (so ~2.2gpm @1000rpm), and the relief valve for the 3.5 equipped trucks is set to a max of 1,309psi.

I'm not sure what size cylinder your kit has, but the difference in flow and pressure sounds reasonable. <img src="/forums/images/graemlins/kewl.gif" alt="" />

'06 Dakota QC 4.7 6sp 4x4
'88 Mighty Max
'77 KZ1000 fun old bike