Stock intake vs performer?

66fs said
I've never seen a cracked J head, good luck with the magnums. I would definitely Magneflux the Magnums.

The opened up Plenum on the stock intake is for a little more power at higher RPM.

I have a couple of cracked J heads. One set had 7 of 8 cylinders cracked.
Some had several cracks in the same cylinder.