well scott dropped his 2.4 manifold to see if his overfueling would stop and has not yet put it back on, that in itself is a gauge on performance increases, i noticed the catch tank ran better with it re routed back to the inlet pipe than breathing atmospheric in terms of torque in lower revs, and ran even better without but i lost a bit of power up top
u see quite a few 2.4 manifolds being sold on ebay but i haven't yet seen a piper manifold being sold 2nd hand - so that says a lot as well