I have said it once and will say it again, biggest bore , then stroke it to the biggest diaplacment. NASCAR does it this way, IRL, Formula 1 they all do it this way. You don't see ANY NASCAR builders running a shorter stroke to get more out of it. They run the biggest bore the rules allow then stroke it to the maximum displacement allowed. When you are trying to squeeze every last HP and foot pound of TQ possible then that is how it is done end of story. I am not talking bracket engine builders or street builders (they should do the same as far as there budget or rules allows) but the guys being paid millions to get 5 more hp do it that way. If NASCAR said you could run a 4 inch stroke with the current bore (4.185)you would see them ALL running 4 inch stroke in a couple weeks, same with 4.5 stroke, bore to stroke ratio be danged they would run as big as possible. If Formula 1 said they could run a 2 inch stroke with the current bore they would all do it and very quickly, you would be shocked how fast they would get it done, they would trade some rod length for stroke also if that was needed.