Downpipe shouldn't need a gasket, it and the turbo should be machine surfaces. Though, with my current downpipe (which I bought because I didn't realize I had better options, I wanted a THDP or an ATR... which you can no longer get) it has a leak around it, so I had to buy a gasket. Not happy about that.
You should see the hot air motor I just picked up complete for $500. Home boy used NA head gaskets, #2 piston has never seen a spark, loose bolts all over, etc etc. He complained it didn't make enough power... no shit?
Run CR42TS gapped at .035