If the manual I have for a 660 is covering a 2002 its 188.31 psi) at 850
r/min. Thats using a stock piston. 9.1 : 1 compresion ratio
Might be a little dust on the Grizzly
But it only gets better, one piece at a time. 98 600 Green Grizzly. 27" ITP MudLites, EPI Clutch Kit, UNI filter, DynoJet kit - Stage 1, HMF exhaust .Murderfied cooling fan motor.
30 year old Simpson's Sears 46" Plow, crappy little winch. Fabricated harness . . .