[undy]

Depending on how much cam and compression you're intending to run the Eboks will outflow and outperform your PIs, hands down. The Ebok also takes top honors in the bang-for-the-buck catagory. Keith's CNC'd stage IIs Eboks will handle a 600+ hp motor, should you decide to go that way. There's not much in the way of aftermarket cast iron. I'm not a big fan of Shelby heads so I can't help much there, other than they're $$$.