I finally succeeded to get it working.
First I used the newer version of SCsoundEdit.
Two I add the new sound files first. I didn't replace the FX_xxxx file.
Three I made a backup of the successful modded sfx.agg file and only then try to replace the background noise which seems to be the source of all corruption. And I finally did it without glitch.
The mod is terrific. Now I could hear unique sound signature for Kilo, Kilo improved, Akula I improved, Akula II, Los Angeles, Improved Los Angeles, and Seawolf as well as seismic and small boat(trawler I think) when they are close and travelling at relatively high speed. Gave me a spook on hearing those different submarine sounds.
Imo it's possible to use this mod in DW. Using SoundEdit and DWEdit(object.eod database edit)
