65Dart: those flow #'s are'nt off of my flowbench so, comparing them directly to these magnums is kind of tough. Here are some #'s off my bench if you wnat to compare:

From left to right: Magnum, Full port 2.02 "587" J head that has ran 11's, Edelbrocks I did for Coke Bottle Kid, and a set of Large port Commando's I just did.

LIFT--MAGNUM---"587"----EBROCK----COMMANDO
.100"--67.3-----62.1-----65.6------69
.200"--132.8----135.2----135.2-----140.1
.300"--196.0----198.7----197.7-----202.5
.400"--225.0----239.8----233.2-----246.4
.450"--238.1----253.9----245.0-----266.0
.500"--250.5----258.4----255.3-----277.1
.550"--257.1----264.9----265.7-----281.2
.600"--259.1----254.6----274.6-----282.9
.650"--259.1----N/A------279.1-----283.0
.700"--259.8----N/A------283.9-----285.3

In all fairness to the Magnum, all 3 other heads have 2.02 valves..... and the "587" J heads are the best low/mid flowing J heads I have ever done, so that is kind of misleading. They just ended up being a REALLY good set of heads. And you can see why IMO the Large Port Commandos are such a great head for the $.

For a more "fair" comparison, here is "Valcuda"'s "596" J heads with full port work and 1.88 Tulip valve next to the magnum:

LIFT--MAGNUM---"596"
.100"--67.3---58.7
.200"--132.8--120.1
.300"--196.0--182.9
.400"--225.0--225.6
.450"--238.1--238.1
.500"--250.5--241.5
.550"--257.1--247.0
.600"--259.1--248.8


And I'm not even going to bother listing race heads as that is comparing apples to oranges. I'll just say, a W-5 has absolutely KILLED every other race head other than a W-8 that has been on my bench.