When I had my heads stock on a 700bb turboed setup I could feel a big difference when I went with a Radius valve job and ported out the heads as well. You will notice big time. Now I didnt dyno to see if they were different results like I should have but you will notice that it will pull a bit harder on the same psi. Also I went with oversized 1mm valves and upgraded springs and JWT500 cams and ported out the heads. The only thing I did not do on my car was the solid lifters. Didnt want it to sound like a v8.