[730RWHP12A]

does anybody know why Mazda moved the leading spark plug down on the series 5 and 6 motors? There must be a reason mazda did this..next question, if you ran the series 5 or 6 housings will it hurt power if your a N/A application? or would you make more power using series 4 or earlier housings? N/A application.. thanks in advance guys!