I'm not real familar with the numbers on any pro comp heads, or what they go for. But most people that are building on a budget might look at some GT40 heads. They can usually be had for real cheap, and are a great upgrade over stock e7's. And if they are ported, that'll give you even greater gains.
P.s. your gonna want to upgrade your fuel system too.
2000 Mustang GT-Former giggle gas addict
1990 Mustang GT w/ Vortech V3
***resident gun idiot***