Hi, I've used motorkote in my good ole tiburon. It sure does good to your engine by reducing friction etc. I personally wouldn't use it in a turbo car for many reasons. I believe high quality full synthetic oils have many additives that protect the engine. Motorkote would be ideal for a tired worn out engine or so. After using it to my old car it sounded quieter and the engine roughness was reduced. I personally would never use it to an STI .my 2c though