With great performance and availability, the GM LS (LS1, -2, -6, -7) engines are an increasingly popular choice for retro-fit street rod and muscle car applications. In stock form, these engines are decent performers but they have much more to offer. And now with the Thumpr™ GM LS Cams you can have all the efficiencies delivered by this modern engine platform with a head turning “old school” hot rod sound and serious performance to back it up. The new Thumpr™ GM LS Cams are compatible with both arbureted and re-tuned electronic fuel injection (EFI) engines and do not sacrifice anything in durability or street manners.