I would like to install custom ai sounds for my Ai aircraft insted of the default sounds in FS9..how do i go about doing this?

There are several AI sound replacements sets here in library but be aware that FS2004 does not provide a method of using different sounds for different individual aircraft. You can only modify the basic group sounds - jet, prop-jet etc.Tips and Tricks for FS2004 Issue 11 also has a discussion of this and a couple of suggested files which you can audition.See tips_ands_tricks_11.zipaisound_1.01.zip would be a good starting point so you can "hear" for yourself what is possible.I would also suggest searching for the name Andrew Berry in the FS2004 Sounds area. He has some good info packaged with several of his files.Hope this is helpful.