Increase Cruise Speed by 15 to 20 Knots! Affordable Ram Air Cowlings and Aerodynamic Speed Stacks for the King Air. Increase cruise speed by 15 to 20 knots with American Aviation's new Ram Air Cowlings and Aerodynamic Speed Stacks. Proven on the Piper Cheyenne and the Cessna Conquest, these products are now certified and available for the King Air 90 and 100 series. Ask the Man Who Flies One. Call Bruce Burk at 800-423-0476 or 208-762-8815 for pricing.