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Boss 302s use this 37x31.8mm valve package and upgraded beehive valvesprings. Necking the valve stems down to improve airflow through the port was tried, but it didn’t prove worth the effort. Sharp eyes might be able to spot how the valve heads are cut back to improve low-lift flow. This tactic was especially productive with the exhaust valve, which uses a 40-degree seat instead of the more typical 45-degree seat to promote low-lift flow.