I particularly like Mitsu's "Scramble!" call when a base is under attack, and the "Check 6!" is good too. I didn't care for Mitsu's P-51D and Spitfire IX engine sounds so I replaced the P-51D eng.wav file with a different engine sound and the Spitfire is now powered by a 1960's-vintage Cooper Grand Prix motor. Climbing up to 10k with the Cooper on full throttle is quite an experience-sounds like its going to vibrate itself apart!

I posted a link in the "Sounds" forum if you want to download some different engine sounds. Cooper, Lotus, Ferrari, Honda - all good!