I went front mount after hours and hours of tuning, mostly road, and I could see my performance, knock patterns, and even boost spool affected by a hot top mount. Since I have went front mount these have all stopped. I am running a Dom 1.5XT-R, which isn't the largest turbo in the world but it's substantial compared to stock. My point is just this, if you are going to buy one, why buy something that already has issues with being right over the motor/turbo? I had mine blanketed, and a full wrap on it as well. I had zero throttle response or spool characteristic change. So it's hard for me to see suggesting putting something on I saw issue with, not trying to argue, just speaking from experience.
All this was done before I got rid of the VF52(it blew up, like previously stated). I have been on front mount ever since and wouldn't dream of going backwards. Like I said, if you are putting out the cash, it's hard to not suggest what I think works better.