A K&N is a quality filter and on a modern ECU controlled air fuel mixture car will not lose any torque or HP. The ECU will easily adjust for +/- 10% or so as needed just as a new or better airflow filter or a dirty filter will cause the need for change.
D BERRY- do you think you would have needed to adjust timing, carb on the 455 after the K&N to see any gains or at least no loss?
Now: 2016 Mustang GT Fastback-Magnetic Metallic, Ford Racing Touring axle-backs, Ford Racing front strut and k-brace, K&N CAI, sound tube delete, 1975 Corvette Coupe-L48, 4-speed
Past Lives: 2001 Corvette Z51 Coupe, 2012 Mustang Grabber Blue Coupe, 2008 Mustang Torch Red Vert, 1988 Mazda RX-7 Vert, 1985 Nissan 300ZX, 1979 Mazda RX-7, 1971 Datsun 240Z, 1972 Fiat 124 Vert, 1971 Chevelle, 1970 Challenger