Quoted from Homepin:6.5 for modern machines
correct and changing it to even 6.4 or 6.6, on many games you'll notice a difference on shots and general difficulty getting harder/easier. ex: Iron Man gets harder when too low, i.e. flat due to brutality of side to side action and outlanes. recommend taking leveling your games seriously and check on them from time to time. You're selling yourself short otherwise.