I mate, yes I have.
Mine doesn't have the standard air box on it currently. My old ep3 (2002) had quite a good sir filter, heat shield and cold air pipe running in it when I bought it. The improvement in engine noise, specifically cross over what very good.
I was kind of disappointed in the 'standard' noise when buying my new one.. the Tegiwa sounds awesome and looks very nice in the engine bay. Only thing I need to get over is the scoop on the exterior, I'd rather not have that, sticks out on a silver car more so than the black ep3s... needs must though
Thanks for your input