Barrett Precision Engines Inc., based in Tulsa, Oklahoma, overhauled general aviation engines and adapted especially Lycoming and also Continental engines to the demands of acrobatics clients, converting one engine model into another.

-The parallel-valve Lycoming O-360 and O.540  became Barrett O-360-X and O-540-X, and the inclined-valve engines became Barrett IO-36O-X and IO-540-X. They built a new IO-390-X from Lycoming parts.

-From Teledyne Continental, Barrett converted the TSIO-550 into the new Barrett-TSIO-550-X.

From appendix 10: They collaborate with Superior Parts that authorizes Barrett to use their products.

"Barrett XP-400, 215 hp"