The ever-experiementing Ted Breaux has this to say :
I had my heads ported back in '94 by a gentleman who is a whiz with 4-valve heads. An article in Super Ford Magazine (Oct '94) featured the heads and flow data. While significant improvements in flow potential were made, they could only be realized in lift ranges beyond the factory cams. Since I had installed larger (stage 2) cams at the time, I was able to realize some benefit. Unless you have Genesis II cams, and anything less than a top-notch exhaust system, this is a pure waste of money.