of the yellow tops. I know greg knows the whole deal behind it but I believe they use to flow 615cc back in the day and now they flow 608cc due to possibly new manufactures. Do not quote me on the complete reason for why there is such a huge variation in the numbers but I do know with 100% they flow 608cc now. Wish Greg would tune in and clear it up some I know he told me once but to busy to look it up.