do you not need to close off the end by the TB? i would think that the pressure would go into the engine & then start pressurizing it (not sure if thats bad or not)
I just always assumed that you would use one of these on sections of the IC at a time..
IE.
connect to the hot IC pipe & block off the end before the IC....check....no leaks, then include with the IC but block off the "cold" end of the IC, works, then move to the end right before the TB
disconnect from the TB, & block off that end & test.