I typed another response but it didnt make it on here…so here goes again.
That noise you hear is most likely the turbo compressor wheel contacting the housing…this can be caused by oil starvation, normal wear, or a dump valve malfunction… If the dump valve doesnt vent that pressure wave it will slam into the throttle valve and or the turbo compressor wheel. If you put a new turbo in make CERTAIN the dump valve works or it will destroy the new turbo. Check that tubo shaft for side to side play…it should be VERY minimal…it will have a little but no more than that…also look for evidence of the wheel grinding into the housing…you will be able to see it. You might find a destroyed compressor wheel. Let us know what you got…