Best headers for magnum 360 into Demon?

I'm not sure of the bolt pattern on Magnum head vs. LA head, but Doug's headers can be had through Autozone sometimes with a pretty decent special discount.

Look for an Autozone discount on them, then call Summit and see if they will price match (it's been known to happen). You may get them quicker from Summit than you would Autozone.

Again check LA bolt pattern vs. Magnum.