Texture Conversion

Hi all. Does anyone know of a generic texture conversion program that can work with any aircraft it is ran on in order to make a 32 bit tex into dxt3? I know some plane download with a specific texture converion exec but I am looking or a converter I can use with any plane. Specifically I would like to use it on the new ifly 744 to try to make it less of a frame hog. Any help? Thanks.