Sorry,your asking about downpipe, same thing some use one and some dont. I just had new turbo installed,the guy used a gasket, once again its what you prefer.
I just used high heat RTV gasket sealer cause there was no gasket at all when I had the downpipe off, it's aftermarket and I suspect the factory had a gasket...also I seem to remember there was a donut gasket somewhere, sorry it's been a couple years.
Factory had no gasket between turbo and the elbow. There was a donut from elbow to down pipe with spring bolts. If you have an aftermarket downpipe it bypasses the elbow so no donut gasket anymore. Copper rtv works. The flanges can get bent from using gaskets. Like said already, that is personal preference.
I don't use any exhaust gaskets. No header gaskets. No downpipe gasket. No gasket between the turbo and header.
If you ever have the heads off (I know this never happens with our cars but if you EVER do) get the surfaces checked for flatness and milled flat if necessary. Do the same for the header flanges, downpipe flange, and turbo surfaces. The factory did not use gaskets. Take the extra step to insure everything is flat and no gaskets are necessary.
