under a load the 383. that cam is not far off a build 355 i did last fall were we had a custom erson roller ground and the pbm heads some what like gm v tech s they just do not crack .you have to watch with the throttle bodys if your going to use one.they will not take any cam they need to idle low .the map get out of wack then its dumping fuel out the tails and sound like a top fueler that 395 cam is used the the boats as well i used one in a mild street engine in a big car