Not trying to dispute you--I ran some PSI springs in testing for my 2010 EMC 367 at 220 lbs on the seat and just under 700 open with those lifters! Of course I only made 35 pulls on the dyno but I was really impressed-a stethoscope on the v-covers and it sounded like a sewing machine.Oh and nothing changed when I went to a PAC beehive with a much lower rate. Just thought I'd share that-as I figured it was not going to workout at all--but it did. J.Rob