That's part of the issue. There is nothing wrong with the OE MoPar combustion chamber. In fact, it's better than most of the junk out there being sold today. To get a closed chamber correct is not that easy. Anyone who has ever worked with a BBC closed chamber head knows what garbage that pig is.
The junk chamber in the W5 head is a crime against horsepower. Chrylser should have been ashamed to put that chamber out there. That's why most W7 heads (if not all of them) came without a chamber. That W5 chamber is J U N K junk but Chrysler gave all the whiners and snivelers what they wanted...a closed chamber head.
As I've pointed out in other threads, the material of the head makes ZERO difference regarding compression ratio AND ignition timing.
Detonation resistance is based as much on chamber SHAPE and plug location as much as cam timing is. Maybe a bit more.
A closed chamber isn't always a good chamber, and no amount of marketing can fix that.
