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The argument for displacement, I will give an example, the Harley Sportster 883-1200 conversion, you replace the 3 inch 883 cylinders and slugs with 3 1/2 inch parts, same 883 heads and gearing... the difference is night and day. Ask anyone who has done it. So its a 1 inch area of displacement across two cylinders, how much displacement is added from goin 3.91 to 4.04 across 8 cylinders?