If you are mechanically inclined, I would say try what KATwo40 has done. He's just getting around to driving/tuning his car. He used the generic T2 flanged bottom mount manifold offered by SSautochrome, and welded a T3 flange onto it. Not that difficult unless you don't have the tools.
zerothread/217193 There is a T3 bottom mount offered on eGay manufactured by OBX that people have been looking at, but been leary of because noone's tried it. I can't find it right now, but it's on there. Just search, I'm sure you'll find it. Other than that, I don't know what to say. The whole bottom mount thing definitely looks stealthy. Especially when you wrap the header, and button everything up real nice. Like tuck wires and all. Hope that helps!