i gained the 4 hp with the foam type vs the twm with cone on the dyno. the cone was ducted to the openings in front by the radiator with a heat shield blocking heat from the radiator and directing air to the filter
not sure what the effects of air flow with the car moving are.Obviously the car was stationary on the dyno. I had the stacks on in both cases. The engine builder had said that the TWM unit created too much turbulence inside it.I had run it like that for anumber of years but decided to check it out while the car was on the dyno