[Dwight Southerland]

Here's a different perspective since I have flowed over 100 different 520 cylinder heads over the years. Back "in the days" there were some ingenious folks who understood the psychology of numbers and their effect on the racer's mind. Sometimes a truly odd part in a common pile could be personally modified for an advantage and then the superiority be attributed to its oddness. If most everybody's 520 heads were 130 cc and yours were 140 cc, the argument is easier to swallow if yours have markings that indicate a different origin. That's not always true, but cases like the 461X heads can be used to further substantiate a new legend. However, 'T' heads are consistently a good choice, if you get my drift.