http://bbs.hitechcreations.com/smf/index.php/board,583.0.htmlTry starting here, I got a custom soundpack setup fairly easily. There's some great tutorials on this thread to get you started. I have Mitsus soundpack and am happy with it. I may need to update as I believe there's a new version available with additional sounds covered.
A suggestion: Make a copy of your original installation files for Aces High, just in case you overwrite something you shouldn't have, you can always "re-instate" the working original game files. As Skuzzy states, DO NOT DELETE GAME FILES!
Good luck.
P.S. If you can change out the 8" cruiser sound to something that won't blow your head off and pop your speakers, the original sound is real heavy...
I believe I heard someone make their own recording of saying "boom" to replace the loud original sound file.