When I dyno tested my old pump gas 511 C.I. six pack motor I tested it with a single stock Fram paper air cleaner, then two of them stacked and then I did the same with K&N elements and then no air cleaner base and finally with the air cleaner base. I saw a little improvement with two elements versus no elements, no where near 100 HP, maybe 3 to 6 HP gain with two elements versus one Using the base only made some small gains also, same thing in the car at the track