I had it running with the 6cyl TB for a while, but it was idling at 6000rpm, which I didn't like. I re-routed the coolant lines, and left it that way. But so far I just ended up changing it back. I think I might have had the gasket in the wrong way, which would explain the high idle, but for now I am going to concentrate on other aspects of performance and such.
The way I see it right now is after the TB, the manifold inlet is going to be the same size, or pretty much the same size. The stock TB makes a smooth transition between the two sizes, where as if you use the 6cyl, its large, then just a big step to the smaller size. Its not worth it without an aftermarket intake manifold IMO.