the original "PlaneAfterburner.wav" sound file was 10mb + and tainted with distortion in "DCS - Afterburner Sound Mod 2014-07-15" from "WineNB". Located in "https://www.digitalcombatsimulator.com/en/files/721823/?sphrase_id=8039692
"PlaneAfterburner.wav" was mainly worked by WineNB and uploaded with Freeware license "Free version, Unlimited distribution". I had successfully cleaned the sound and cut short the file size to reduce system resource usage.
I make some experimental sound upgrade and packed together with tuned sdef files. Sound affected for Su-25, Su-25T, Su-25TM, Su-27, Su-33, Su-30, the cockpit afterburner and plane afterburner sound work for all.
updated 29th September 2017, included with MiG-29A, MiG-29S, MiG-29G, MiG-31, all MiG sound file was shared, all MiG was affected. Just extract the zip into "DCS World\Sound" folder.