My experience with the 440 Source heads has been good (although very limited) so far. The springs and retainers were changed because of the lift on the cam. This was recommended by 440 Source on their website. The heads appeared as advertised with no obvious flaws. They were given a once over by my machinist and I took them home and bolted them on. I've only broken in the engine at this point and done some tuning so time will tell. I'm also using their rockers and stroker kit so we'll see how this all holds up over the long run.
