SFI is the certification authority for race parts. If you dont plan on doing 10s you dont need an SFI blancer. Basicly an SFI balacer is one slug of metal where a stock is actually 2 with a rubber bonding agent between the two parts. High reving race engines tend to sling these appart thus the one piece SFI balancer. I severly doubt you get the balancer with the pulley for 60 bucks more though. The ones for the V6 we had made were right at 300 a piece our cost.