Fitting a non-standard turbo manifold using an adaptor plate

[(steven)]

When thinking about turbo-charging an N/A car one of the more difficult/expensive parts of the operation is getting a custom manifold built to house the turbo.

One of the more 'interesting' solutions I've come across is digging out a turbo and exhaust manifold from an existing car and then using an adaptor plate to bolt the non-standard manifold to the engine of your choice. (The adaptor plate being a laser cut chunk of metal with different holes and stud spacing on either side).

Anyone had any experience of this? Do they work? Obviously your going to take some performance hit as this is a bodge rather than a solution but compared to having custom manifolds made up it seems like a cheaper solution. How far can you go with this stuff? Is there a limit to which you can match a pre-made manifold to an engine it wasn't intended for?

All opinion, informed or otherwise appreciated (although the former would be nice)