I am not trying to be argumentative but you can't make blanket statements about things and expect no rebuttal. I had a CT20 on my 3TGTE and it would rev as far as the management would allow it. The turbo you had must have been damaged to restrict the airflow as you say. I am trying to answer the guys question regarding fitting a turbo to an 18RG on a budget not jump on the "those turbos are shit, you need a GT25 or it won't run" bandwagon. If the CT20 is in serviceable order it will work on an 18RG, it won't make huge power but nothing will at 6 psi on a budget.