Not much all three are about the same. Unless it's on a big inch (416 plus cubic inch or bigger) small block stroker more value/better off throwing them in the smelter at Edelbrock and hoping there is enough aluminum to cast a performer rpm or rpm air-gap. If your going to use one, choose the one with the curved, sweeping runners, I think the 340 torker has the best profile and streetable torque curve for that kind of build on the street, but only with a build for 3000-6000 rpm. Most all street builds much heavier than a go kart will benefit much more from a performer rpm or air-gap. Hughes can do some porting on the 340 Torker that will extend the RPM range, and any of these manifolds can be useful if you need to kill off some bottom end torque to maintain traction.
