i am using those heads.it took me fifty hours to port and polish those things.if they are ported correctly,usally barrel hogged and oversized first, you could easily run a tunnel.but why on the street? use a performer rpm or an air gap dual plane manifold which is still pretty high and has lots of plenum but with better bottom and mid response.i just recently ran a 2.35 second hundred foot run in a 4200pound truck.that is 56 miles per hour in 2,35 seconds with that set up . of coarse i have more than just that but,i can drive to work and not have to wait an hour for the manifold to warm up..