Late to the party. Its been around a while but I couldnt get info on it either.
I bought the p4529368 pump and had it tested by Ryan Brown. The MP catalog had its pressure rating at 9.5 psi but it turned out to be a much more civilized 7 psi. That's a 1/2 psi less than the M6270 Carter "competition" pump was rated, and tested at.
Only problem with the MP p4529368 pump is interference with the '70 and up water pumps with passenger side inlet. Wish someone wouldf make a an aluminum driver side pump again.
http://www.heritech.org/cuda/fueldelv.html#Pump%20Fit%20IssuesI've had good luck with Holley's 110 mechanical pump on my 340.
PS. The other time (besides idling) those high cutoff pressures really bite you is when lifting off the gas at mid to higher rpm.
