According to the Bro-Science book (3rd ed, 2007) a higher concentration gear causes more PIP than standard 200-250mg/ml.
This makes perfect sense as more solvents are needed to make the high concentration gear and some people are allergic to solvents and get a bad PIP. I would like to point out that other reason for a bad PIP is a poor injection technique (ie. not sticking needle deep enough and/or injecting too fast and/or simply injecting too much gear at once)
Never run GP T400, but I've run other brands. I remember running Lixus T400 (200e and 200c) and Sciroxx T450 (blend of 4 or 5 esters) with zero PIP. At the time I pinned test and EQ e5d and NPP e2d, only got pip when my injection schedule indicated that I had to take all 3 on one day. I chose to pin 3 ml in my quads and deal with the PIP, but it could easily avoided if the 3ml was split into 2 injections.