I knew a guy from another Penis Enlargement site who had massive girth gains from doing this. He said he would put a ton of vaseline on his dick to give it the nutrients it needed to expand all night. He wore a
sleeve to ensure that pressure did not leak out, and would wake up every 3 hours or so, release the pressure, then pump back up. I believe his pressure range was 2-3 hg.
I never tried it, and it does sound dangerous, but he claimed it was the only source of his gains.