How much compression with a Magnum?

Interesting that the cr ratio of the 5.2 was a little higher than the 5.9. Don't forget that also carbon deposits in the first 10k Mike's are supposed to bump the cr up by .5...do I believe that, no, but there is probably an increase to a lesser degree. In other words if you are trying to get your cr right up to the edge of detonation, it's a good idea to leave yourself a little wiggle room. And in terms of actual performance to me it's just not worth it. But to each his own, if you really want to be right on the edge, I've always heard to keep it under 9.5:1