I ve been running a bhaf for sometime. I just made a plate to seperate it from the turbo. I sealed it to the hood. Its not done by anymeans, nor does it seal off the engine. Really just a seperator between the filter and the turbo. The egts droped about 75 degrees at cruise. Remarkable to me, and I can get into more with out spiking the egt as quick.

 

Makes sense to me. Your isolating it away from the underhood heat more.