for whatever reason, against conventional wisdom, my usage of oem exhaust manifold gaskets with copper rtv works. Perhaps it's because I'm using an OEM cast manifold that doesn't move around like a fabbed one likely would. I only used goo in the joint from manifold to piping, but I think I used a steel shim gasket at the turbine.
If I was running 20psi of boost and had my 2:1 backpressure maybe I'd be a lot more leaky than I am =)