I have a 565 with afr 335 heads, ross pistons, 10.5 comp. running 93 octane. the chambers are cnc" to 121cc. when we dyno it we had it at 32 degrees until fuel cruve was good then the dyno operator said lets try 30 degrees and it made about 5 more horse and trq so we left it. I have had a guy from reher Morrison told me he wish I had tried 36 so does anybody know where those heads tend to run best at? right now my combination is player hell on my header coating, after 30 hours of running I am getting them recoated, I run them dry with muffler inserts, last day out I ran them open and they ran a lot cooler so I am going to try shotguns instead.