If your engine has had modifications that has altered its torque curve (intake, cam, etc.) then a converter should be used that allows the engine to operate in this new torque range. A mildly loose converter helps prevent the engine feeling loaded down at low RPM. Listed for GM turbo 350 and 400. These are mild converters for street rod use. HoleShot converters are a better quality converter than the TorkMaster converters. Stall listings are approximate.