Okay, considering the rest of your setup, different heads are a waste of money unless there is physically something wrong with your current heads- you're honestly not even taking full advantage of what you already have. Pull your current heads and inspect them- if in good shape have them freshened and clean up the ports. Not all Magnum heads crack- mostly ones that have had an overheating issue in their past. The current iteration of the EQ replacement head offers no real performance increase over the stockers- they're not what the old Kiwi EQs were.
