...then dougs spec is not suitable...maybe different cam timing or camshaft to eliminate that 2bar surge or ported shroud would sort it...
your engine should be able to consume what the turbo can give at any rpm otherwise you are having to compromise by getting round it.
..i will say my MAD engine didnt have any surge at 2bar on the gt35 non ported shroud..but i cant say what cams or timing it had.
...be interesting to know wether Rod has had to map around or compromise on his new turbo?