I have vic jr's on my 351w. I love them. I used to have holley systemax II heads on my 351w. I picked up 4 mph on a 1/8 mile tarck when I swapped to these heads. I just bolted them on. My 11.5 1/4 mile time was with the holley heads. I hope to see what I have picked up in the 1/4 mile with...