I've looked at the 3PD site and investigated using 4 pot turbo's but I don't think its as easy as some suggest. I certainly haven't found any clear explanation of what I would need. Maybe I just can't use FB, I'm not a fan. For example the GT1749V from a mark4 golf TDI130: Whilst the manifold would fit on the engine and downpipe, the EGR is in completely the wrong position and orientation and could foul the oil feed pipe, the intake air tube and boost pipe would not fit. I'm not suggesting these problems can't be overcome, but I can't find anywhere that tells me what other adaptions I might need to succeed. Also not sure if it would need mapping.
Trevor