Hmm.. don't think you'll need 15-20k that much.
Injectors 740CC - $800 or so
FMIC - $600
Turbo GT3037 - $1,700 or so
Turbo Kit - $1,000
Fuel Pump - $250
AFM w/ plug - $330
power fc - $1,500
Twin Plate Clutch - $1,800
Coilovers - $1,800
Better Brake Pads - $250
Labour + Tune - $2,000
There you go . Should be less than 15k
However, how long your engine with stock internals will last with 300 rwkw, i do not know