5.9 mods

Yes as in stock pistons. If I could go back I'd bump the compression a little but that's way down the line hopefully. Are your heads stock, but ported? Kegger intake?
Speedmaster iron magnums, worked w/ 1.94/1.60 valves @61cc, kegger intake port matched. It took work to make them that way, but you can get there with stockers ported. Have yet to get a tune from hemifever but I'm going to.
Stock cam isnt the limiting factor, the heads/springs and cyl pressure are.
Mill the heads to 60cc and port them with verified numbers to know.