Well I know for UP/DP you need to switch out most the gaskets, most def the gaskets touching the turbo. But do I need new gaskets for the UP connecting to the exhaust manifold? I'm wanting a shorty DP, so would i need a gasket connecting DP to midpipe? Should i buy OEM Subaru gaskets, some generic ones from NAPA, or these " Cu-Seal Embossed Copper Gaskets" ? Copper ones look damn nice though.
Its always better to buy new gaskets when switching parts out. A new gasket acts like a fresh seal, with an old gasket the seal isn't nearly as good. If the gaskets are fairly new, less than one year old, you could probably get away without it. The OE gaskets are fine. If you are buying the pipes new, they normally come with the gaskets also.