I remember a mate, had a G60'd polo..
He just bolted a non ported with stock pulley g60 and the sls conversion kit and he had 1bar of boost and the car made 152hp..
Note that the engine was totally stock.
So, if you have gt inlet, bigger tb, at least 55mm exhaust, and a g40 specific 252/276 camshaft, with a 70mm pulley i guess will boost up to 1-1.1 bar