Thanks for the input guys...
So from what I can gather (please correct me if I'm wrong)
GTI intercooler is the same as the ED30
Turbo in the ED30 is the K04
DV Is spaced from the turbo in the ED30, non spaced in the standard GTI
So - I take it if my car's a standard GTI with custom remap, all I would need to do for a safe and reliable upgrade is to put a spacer in for the DV (I'd probably go for a Forge with spacer), get the K04 turbo fitted and the custom remap amended.
I've found a nice site in the US with the turbo upgrade for 950 Pounds, so this looks like a good cost effective mod. Suggestions please (up to 300-310bhp with custom remap) if this is a relatively safe mod to carry out....