When I had the M56 (N/A Japanese V8 420HP) I took the time to do baseline dynos. Then swapped out the air filters (M56 has two separate ducts/filters) with K&N. Re-dyno and no real difference, within % of error, at the wheels as measurable on the dyno.
Not all vehicles are the same, some will benefit from a swap odds are. Just depends on stock design and how easy it already breathes.