Conforming and non-conforming club heads, difference?

[putput]

So I was looking around ebay being bored and noticed that there were some “non-conforming” clubs that were selling for allot more, I know that they banned the making of them on the PGA but really is there a huge difference between the two? Why? Has anyone used both and can tell the difference?

[RocketSauce]

i dont really know. ive heard some people say they do make a difference, and others say they dont unless you have a 115mph swing speed. ive heard the old Callaway ERC Hot driver was a bomber. id also love to try one of those Wishon .900 COR driver heads. im curious about this myself

[RocketSauce]

here is the way someone explained the whole COR thing to me. makes sense:

"There have been numerous studies on this, and yes...the higher the swing speed..the greater the distance advantage...just like the ball will naturally go further with increase in head speed.
The coefficient of reinstitution is a physical measurement of how much energy is returned when two objects collide (the head and the ball)..100% cor would return all the energy..imagine if you drop a ball from 6 feet..it would bounce back up to a height of 6 feet..this is actually impossible. so a clubhead with .830 cor will return 83% of the energy...an .870 cor will return 87% and so on.So infact there is no swing speed limit as to when these "work"...the law of physics dictates they "work' at any head speed."

i'd love to pick one of these up someday to find out for myself

[putput]

here is the way someone explained the whole COR thing to me. makes sense:

Ok all of this makes sense... but what is up with the non-conforming part, what exactly makes it non-conforming club head?

If the case is that at any point .cor value is equal to the amount of energy is transferred, why wouldn’t they allow the maximum amount at any given club in regulation?