nick im not sure if you got this, but a custom turbo kit is going on group buy right now. Its a garret bolt on kit. Stock manifold, and uses internal wastegate. im sure you can upgrade external if you make a diff mani but there going for around 1400 bolts up to gen 3 too. im waiting for dyno numbers to see what kinda power they make before i decide to get one or not but they say the turbo easily pushes 300-400whp

http://thespeedfactor.com/turbo_mr2.html