Agreed, especially F-14 sounds pretty awful. Heatblur just considers those sounds good and pretty final, although it sounds pretty much not like at Tomcat at all. I'm not sure are there much to do by modding. I've tried myself by replacing those external engine sounds with F-16 samples but they don't really sound what it's suppose to.
F-18 on the other hand sounds quite good, especially with Echo-19's mod.